diff --git a/service/models/operations/calibrate.py b/service/models/operations/calibrate.py
index bb9ddd6..062c3a6 100644
--- a/service/models/operations/calibrate.py
+++ b/service/models/operations/calibrate.py
@@ -25,19 +25,12 @@ class CalibrateExtra(BaseModel):
     num_iterations: int = Field(
         1000, description="Optional field for CIEMSS calibration", example=1000
     )
-    lr: float = Field(
-        0.03, description="Optional field for CIEMSS calibration", example=0.03
-    )
     verbose: bool = Field(
         False, description="Optional field for CIEMSS calibration", example=False
     )
     num_particles: int = Field(
         1, description="Optional field for CIEMSS calibration", example=1
     )
-    # autoguide: pyro.infer.autoguide.AutoLowRankMultivariateNormal
-    solver_method: str = Field(
-        "dopri5", description="Optional field for CIEMSS calibration", example="dopri5"
-    )
 
 
 class Calibrate(OperationRequest):
@@ -46,6 +39,21 @@ class Calibrate(OperationRequest):
     dataset: Dataset = None
     timespan: Optional[Timespan] = None
     policy_intervention_id: str = Field(None, example="ba8da8d4-047d-11ee-be56")
+    learning_rate: float = Field(
+        0.03, description="Optional field for CIEMSS calibration", example=0.03
+    )
+    solver_method: str = Field(
+        "dopri5",
+        description="Optional field for CIEMSS calibration",
+        example="dopri5",
+    )
+
+    # https://github.com/ciemss/pyciemss/blob/main/pyciemss/integration_utils/interface_checks.py
+    solver_step_size: float = Field(
+        None,
+        description="id from a previous calibration",
+        example=1.0,
+    )
     extra: CalibrateExtra = Field(
         None,
         description="optional extra system specific arguments for advanced use cases",
@@ -74,6 +82,11 @@ def hook(progress, _loss):
                     logging.info(f"Calibration is {progress}% complete")
                 return None
 
+        extra_options = self.extra.dict()
+        solver_options = {}
+        if self.solver_step_size is not None:
+            solver_options = {"step_size": self.solver_step_size}
+
         return {
             "model_path_or_json": amr_path,
             "start_time": self.timespan.start,
@@ -82,8 +95,11 @@ def hook(progress, _loss):
             "data_path": dataset_path,
             "static_parameter_interventions": static_interventions,
             "progress_hook": hook,
+            "lr": self.learning_rate,
+            "solver_method": self.solver_method,
+            "solver_options": solver_options,
             # "visual_options": True,
-            **self.extra.dict(),
+            **extra_options,
         }
 
     class Config:
diff --git a/service/models/operations/simulate.py b/service/models/operations/simulate.py
index 2aeeebb..45da154 100644
--- a/service/models/operations/simulate.py
+++ b/service/models/operations/simulate.py
@@ -2,8 +2,6 @@
 
 from typing import ClassVar, Optional
 from pydantic import BaseModel, Field, Extra
-
-
 from models.base import OperationRequest, Timespan
 from models.converters import (
     fetch_and_convert_static_interventions,
@@ -28,7 +26,18 @@ class Simulate(OperationRequest):
     model_config_id: str = Field(..., example="ba8da8d4-047d-11ee-be56")
     timespan: Timespan = Timespan(start=0, end=90)
     policy_intervention_id: str = Field(None, example="ba8da8d4-047d-11ee-be56")
-    step_size: float = 1.0
+    solver_method: str = Field(
+        "dopri5",
+        description="Optional field for CIEMSS calibration",
+        example="dopri5",
+    )
+    logging_step_size: float = 1.0
+    # https://github.com/ciemss/pyciemss/blob/main/pyciemss/integration_utils/interface_checks.py
+    solver_step_size: float = Field(
+        None,
+        description="id from a previous calibration",
+        example=1.0,
+    )
     extra: SimulateExtra = Field(
         None,
         description="optional extra system specific arguments for advanced use cases",
@@ -51,14 +60,20 @@ def gen_pyciemss_args(self, job_id):
             extra_options.pop("inferred_parameters"), job_id
         )
 
+        solver_options = {}
+        if self.solver_step_size is not None:
+            solver_options = {"step_size": self.solver_step_size}
+
         return {
             "model_path_or_json": amr_path,
-            "logging_step_size": self.step_size,
+            "logging_step_size": self.logging_step_size,
             "start_time": self.timespan.start,
             "end_time": self.timespan.end,
             "static_parameter_interventions": static_interventions,
             "dynamic_parameter_interventions": dynamic_interventions,
             "inferred_parameters": inferred_parameters,
+            "solver_method": self.solver_method,
+            "solver_options": solver_options,
             **extra_options,
         }
 
diff --git a/tests/examples/calibrate/input/request.json b/tests/examples/calibrate/input/request.json
index 3229711..e4f3d0f 100644
--- a/tests/examples/calibrate/input/request.json
+++ b/tests/examples/calibrate/input/request.json
@@ -14,13 +14,13 @@
 		"start": 0,
 		"end": 90
 	},
+	"learning_rate": 0.3,
+	"solver_method": "dopri5",
 	"extra": {
 		"num_samples": 100,
 		"start_time": -1e-10,
 		"num_iterations": 1000,
-		"lr": 0.03,
 		"verbose": false,
-		"num_particles": 1,
-		"method": "dopri5"
+		"num_particles": 1
 	}
 }