diff --git a/src/g5505_file_reader.py b/src/g5505_file_reader.py
index 0865f15..a00a817 100644
--- a/src/g5505_file_reader.py
+++ b/src/g5505_file_reader.py
@@ -135,6 +135,7 @@ def read_txt_files_as_dict(filename : str , work_with_copy : bool = True ):
             separator = config_dict[key].get('separator',separator).replace('\\t','\t')
             table_header = config_dict[key].get('table_header',table_header)
             timestamp_variables = config_dict[key].get('timestamp',[])
+            datetime_format = config_dict[key].get('datetime_format',[])
 
             description_dict = {}
             link_to_description = config_dict[key].get('link_to_description',[]).replace('/',os.sep)
@@ -210,7 +211,28 @@ def read_txt_files_as_dict(filename : str , work_with_copy : bool = True ):
             
 
             df_categorical_attrs['timestamps'] = df_categorical_attrs[timestamp_variables].astype(str).agg(' '.join, axis=1)
+
+            valid_indices = []
+            if datetime_format:
+                df_categorical_attrs['timestamps'] = pd.to_datetime(df_categorical_attrs['timestamps'],format=datetime_format,errors='coerce')
+                valid_indices = df_categorical_attrs.dropna(subset=['timestamps']).index 
+                df_categorical_attrs = df_categorical_attrs.loc[valid_indices,:]
+                df_numerical_attrs = df_numerical_attrs.loc[valid_indices,:]
+
+                df_categorical_attrs['timestamps'] = df_categorical_attrs['timestamps'].dt.strftime(config_dict['default']['desired_format'])
+                startdate = df_categorical_attrs['timestamps'].min()
+                enddate = df_categorical_attrs['timestamps'].max()
+
+                df_categorical_attrs['timestamps'] = df_categorical_attrs['timestamps'].astype(str)
+                #header_dict.update({'stastrrtdate':startdate,'enddate':enddate})
+                header_dict['startdate']= str(startdate)
+                header_dict['enddate']=str(enddate)
+
             df_categorical_attrs = df_categorical_attrs.drop(columns = timestamp_variables)
+            
+                
+                #df_categorical_attrs.reindex(drop=True)
+                #df_numerical_attrs.reindex(drop=True)