diff --git a/converters/honeydew/README.md b/converters/honeydew/README.md
index 4419862b..a4a4bbed 100644
--- a/converters/honeydew/README.md
+++ b/converters/honeydew/README.md
@@ -89,7 +89,7 @@ uv run pytest
 ## Limitations
 
 - **One source dataset per entity**: Honeydew entities can have multiple source dataset files; the converter always generates exactly one, because an Ossie `dataset` block describes a single table or SQL query.
-- **Datatype inference**: Ossie fields have no explicit datatype; the converter infers Honeydew datatypes from the `dimension.is_time` flag (`timestamp`) and the presence/absence of the `dimension` key (`string` vs `number`).
+- **Datatype inference**: an Ossie field's `datatype` maps to the Honeydew datatype (`String`→`string`, `Integer`→`number`, `Decimal`/`Float`→`float`, `Boolean`→`bool`, `Date`→`date`, `Time`→`time`, `DateTime`/`DateTimeTz`→`timestamp`). Honeydew has no exact-decimal or timezone-aware type, so `Decimal` and `DateTimeTz` are approximated. Fields that omit `datatype` (or declare `Opaque`) fall back to inference from the `dimension.is_time` flag (`timestamp`) and the presence/absence of the `dimension` key (`string` vs `number`). On the return trip the Honeydew datatype becomes the Ossie `dimension` shape, not a `datatype` — so `Ossie → Honeydew → Ossie` does not preserve the declared `datatype`. Ossie `metric.datatype` is not read; Honeydew metrics are always emitted as `number`.
 - **Honeydew SQL expressions**: Calculated attributes and metrics use Honeydew's `entity.attribute` reference syntax. These are exported as `ANSI_SQL` dialect expressions in Ossie; they remain valid for round-tripping but may not run on other databases without adaptation.
 - **Perspectives and domains**: Not converted (no Ossie equivalent).
 - **Connection expressions** (`connection_expr`): Preserved in `HONEYDEW` custom extensions on the Ossie relationship and restored on the return trip.
diff --git a/converters/honeydew/src/ossie_honeydew/converter.py b/converters/honeydew/src/ossie_honeydew/converter.py
index 33793e74..6946ada7 100644
--- a/converters/honeydew/src/ossie_honeydew/converter.py
+++ b/converters/honeydew/src/ossie_honeydew/converter.py
@@ -47,6 +47,25 @@
 _LEGACY_OSSIE_METADATA_SECTION = "osi"
 _HD_ATTR_KEYS = ("display_name", "hidden", "folder", "format_string", "timegrain")
 
+# Ossie's portable datatype vocabulary (core-spec 'datatypes' enum) mapped onto
+# Honeydew's (bool, date, float, number, string, time, timestamp). Honeydew's
+# "number" is integral and "float" is approximate, so Decimal — exact base-10,
+# but not integral — maps to "float" as the closest available type. Honeydew has
+# no timezone-aware type, so DateTimeTz also lands on "timestamp". "Opaque" is
+# left out on purpose: it carries no portable meaning, so those fields keep
+# falling back to the dimension-shape heuristic.
+_OSSIE_TO_HONEYDEW_DATATYPE = {
+    "String": "string",
+    "Integer": "number",
+    "Decimal": "float",
+    "Float": "float",
+    "Boolean": "bool",
+    "Date": "date",
+    "Time": "time",
+    "DateTime": "timestamp",
+    "DateTimeTz": "timestamp",
+}
+
 
 class HoneydewConversionError(Exception):
     """Raised when conversion between Ossie and Honeydew fails."""
@@ -442,9 +461,19 @@ def _pick_ansi_expression(expression: Any, field_name: str) -> str | None:
 
 
 def _ossie_field_to_honeydew_datatype(field: dict[str, Any]) -> str:
+    """Pick the Honeydew datatype for an Ossie field.
+
+    A Honeydew datatype round-tripped through a ``HONEYDEW`` custom extension
+    wins, then the field's declared ``datatype``. Fields that declare none (or
+    declare ``Opaque``) fall back to inferring the type from the shape of
+    ``dimension``.
+    """
     hd_ext = _get_honeydew_extension(field)
     if hd_ext.get("datatype"):
         return hd_ext["datatype"]
+    declared = field.get("datatype")
+    if isinstance(declared, str) and declared in _OSSIE_TO_HONEYDEW_DATATYPE:
+        return _OSSIE_TO_HONEYDEW_DATATYPE[declared]
     dimension = field.get("dimension")
     if isinstance(dimension, dict) and dimension.get("is_time"):
         return "timestamp"
diff --git a/converters/honeydew/tests/test_ossie_honeydew_converter.py b/converters/honeydew/tests/test_ossie_honeydew_converter.py
index d83523b4..d9e4410f 100644
--- a/converters/honeydew/tests/test_ossie_honeydew_converter.py
+++ b/converters/honeydew/tests/test_ossie_honeydew_converter.py
@@ -183,9 +183,31 @@ def test_parse_ossie_source(source, expected_sql, expected_type):
 
 
 @pytest.mark.parametrize("field,expected_dt", [
+    # Declared datatype wins over the dimension-shape heuristic
+    ({"datatype": "String"}, "string"),
+    ({"datatype": "Integer"}, "number"),
+    ({"datatype": "Decimal"}, "float"),
+    ({"datatype": "Float"}, "float"),
+    ({"datatype": "Boolean"}, "bool"),
+    ({"datatype": "Date"}, "date"),
+    ({"datatype": "Time"}, "time"),
+    ({"datatype": "DateTime"}, "timestamp"),
+    ({"datatype": "DateTimeTz"}, "timestamp"),
+    ({"datatype": "Boolean", "dimension": {"is_time": False}}, "bool"),
+    ({"datatype": "Date", "dimension": {"is_time": False}}, "date"),
+    # is_time is a role flag, not a type: a year grain stays an Integer
+    ({"datatype": "Integer", "dimension": {"is_time": True}}, "number"),
+    # No usable datatype → fall back to the dimension-shape heuristic
+    ({"datatype": "Opaque", "dimension": {"is_time": True}}, "timestamp"),
+    ({"datatype": "Opaque"}, "number"),
+    ({"datatype": "nonsense"}, "number"),
+    ({"datatype": {"not": "a string"}, "dimension": {"is_time": False}}, "string"),
     ({"dimension": {"is_time": True}}, "timestamp"),
     ({"dimension": {"is_time": False}}, "string"),
     ({}, "number"),
+    # A round-tripped Honeydew datatype outranks the declared one
+    ({"datatype": "String",
+      "custom_extensions": [{"vendor_name": "HONEYDEW", "data": '{"datatype": "bool"}'}]}, "bool"),
 ])
 def test_ossie_field_to_honeydew_datatype(field, expected_dt):
     assert _ossie_field_to_honeydew_datatype(field) == expected_dt
@@ -571,6 +593,29 @@ def test_check_safe_path(rel_path, expected):
          "key_dataset": "li", "relations": []},
         id="composite-pk",
     ),
+    # ── declared datatypes reach the dataset attributes ───────────────────────
+    pytest.param(
+        {"name": "m", "datasets": [{"name": "orders", "source": "db.s.orders", "fields": [
+            {"name": "is_rush", "datatype": "Boolean",
+             "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "is_rush"}]}},
+            {"name": "ordered_on", "datatype": "Date", "dimension": {"is_time": True},
+             "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "ordered_on"}]}},
+            {"name": "qty", "datatype": "Integer",
+             "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "qty"}]}},
+            {"name": "note", "datatype": "Opaque", "dimension": {"is_time": False},
+             "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "note"}]}},
+        ]}]},
+        "schema/orders/datasets/orders.yml",
+        {"type": "dataset", "entity": "orders", "name": "orders",
+         "sql": "db.s.orders", "dataset_type": "table",
+         "attributes": [
+             {"column": "is_rush", "name": "is_rush", "datatype": "bool"},
+             {"column": "ordered_on", "name": "ordered_on", "datatype": "date"},
+             {"column": "qty", "name": "qty", "datatype": "number"},
+             {"column": "note", "name": "note", "datatype": "string"},
+         ]},
+        id="declared-datatypes",
+    ),
 ])
 def test_ossie_to_honeydew_file_content(model, path, expected):
     files = convert_ossie_to_honeydew(_ossie(model))
@@ -1386,6 +1431,26 @@ def test_fields_to_honeydew_complex_sql_goes_to_calc():
                            "datatype": "number", "sql": "price * 0.9"}]
 
 
+def test_fields_to_honeydew_uses_declared_datatype():
+    fields = [
+        {"name": "is_active", "datatype": "Boolean",
+         "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "is_active"}]},
+         "dimension": {"is_time": False}},
+        {"name": "shipped_on", "datatype": "Date",
+         "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "shipped_on"}]},
+         "dimension": {"is_time": True}},
+        {"name": "disc", "datatype": "Float",
+         "expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "price * 0.9"}]}},
+    ]
+    dataset_attrs, calc_attrs = _fields_to_honeydew(fields, "orders")
+    assert dataset_attrs == [
+        {"column": "is_active", "name": "is_active", "datatype": "bool"},
+        {"column": "shipped_on", "name": "shipped_on", "datatype": "date"},
+    ]
+    assert calc_attrs == [{"type": "calculated_attribute", "entity": "orders", "name": "disc",
+                           "datatype": "float", "sql": "price * 0.9"}]
+
+
 def test_fields_to_honeydew_missing_name_raises():
     fields = [{"expression": {"dialects": [{"dialect": "ANSI_SQL", "expression": "col"}]}}]
     with pytest.raises(HoneydewConversionError, match="missing 'name'"):