diff --git a/docs/source/cases_specification.rst b/docs/source/cases_specification.rst
index b0c2f14..ea5d9f5 100644
--- a/docs/source/cases_specification.rst
+++ b/docs/source/cases_specification.rst
@@ -54,6 +54,9 @@ The following header section elements (denoted as `header-lines` above) are defi
     * If no `CosimExecution` object is provided, but a `OspSystemStructure.xml` file is found in the same folder as the `.cases` file,
       this file is assumed as the system definition file and a `CosimExecution` object is instantiated internally.
     * A system structure file can be explicitly specified and will be used to generate a `CosimExecution` object.
+*logLevel* (optional)
+    Log level of the simulator. Per default the level is set to FATAL,
+    but it can be set to TRACE, DEBUG, INFO, WARNING, ERROR or FATAL (e.g. for debugging purposes)
 *timeUnit* (optional)
     The unit of time the independent variable relates to, e.g. "second"
 *variables* (mandatory)
diff --git a/sim_explorer/case.py b/sim_explorer/case.py
index e3b8d4a..f3ec7b1 100644
--- a/sim_explorer/case.py
+++ b/sim_explorer/case.py
@@ -8,6 +8,7 @@
 from pathlib import Path
 from typing import Any, Callable
 
+from libcosimpy.CosimLogging import log_output_level, CosimLogLevel
 import matplotlib.pyplot as plt
 import numpy as np
 
@@ -530,7 +531,7 @@ def __init__(self, spec: str | Path, simulator: SimulatorInterface | None = None
         self.file = Path(spec)  # everything relative to the folder of this file!
         assert self.file.exists(), f"Cases spec file {spec} not found"
         self.js = Json5(spec)
-        #        self.spec = self.js.js_py
+        log_level = CosimLogLevel[self.js.jspath("$.header.logLevel") or "FATAL"]
         if simulator is None:
             modelfile = self.js.jspath("$.header.modelFile", str) or "OspSystemStructure.xml"
             path = self.file.parent / modelfile
@@ -540,11 +541,13 @@ def __init__(self, spec: str | Path, simulator: SimulatorInterface | None = None
                     system=path,
                     name=self.js.jspath("$.header.name", str) or "",
                     description=self.js.jspath("$.header.description", str) or "",
+                    log_level = log_level,
                 )
             except Exception as err:
                 raise AssertionError(f"'modelFile' needed from spec: {err}") from err
         else:
             self.simulator = simulator  # SimulatorInterface( simulator = simulator)
+            log_output_level( log_level)
 
         self.timefac = self._get_time_unit() * 1e9  # internally OSP uses pico-seconds as integer!
         # read the 'variables' section and generate dict { alias : { (instances), (variables)}}:
diff --git a/sim_explorer/simulator_interface.py b/sim_explorer/simulator_interface.py
index f3cc0e8..f789ffc 100644
--- a/sim_explorer/simulator_interface.py
+++ b/sim_explorer/simulator_interface.py
@@ -7,6 +7,7 @@
 from zipfile import BadZipFile, ZipFile, is_zipfile
 
 from libcosimpy.CosimEnums import CosimVariableCausality, CosimVariableType, CosimVariableVariability  # type: ignore
+from libcosimpy.CosimLogging import log_output_level, CosimLogLevel
 from libcosimpy.CosimExecution import CosimExecution  # type: ignore
 from libcosimpy.CosimManipulator import CosimManipulator  # type: ignore
 from libcosimpy.CosimObserver import CosimObserver  # type: ignore
@@ -65,6 +66,8 @@ class SimulatorInterface:
         description (str)="": Optional possibility to provide a system description
         simulator (CosimExecution)=None: Optional possibility to insert an existing simulator object.
            Otherwise this is generated through CosimExecution.from_osp_config_file().
+        log_level (CosimLogLevel): Per default the level is set to FATAL,
+           but it can be set to TRACE, DEBUG, INFO, WARNING, ERROR or FATAL (e.g. for debugging purposes)
     """
 
     simulator: CosimExecution
@@ -75,6 +78,7 @@ def __init__(
         name: str | None = None,
         description: str = "",
         simulator: CosimExecution | None = None,
+        log_level: CosimLogLevel = CosimLogLevel.FATAL,
     ):
         self.name = name  # overwrite if the system includes that
         self.description = description  # overwrite if the system includes that
@@ -87,6 +91,7 @@ def __init__(
             self.simulator = self._simulator_from_config(self.sysconfig)
         else:
             self.simulator = simulator
+        log_output_level( log_level)
         self.components = self.get_components()  # dict of {component name : modelId}
         # Instantiate a suitable manipulator for changing variables.
         self.manipulator = CosimManipulator.create_override()