diff --git a/lib/tdm_ripper.cpp b/lib/tdm_ripper.cpp
index f631ddb..9d5ebf0 100644
--- a/lib/tdm_ripper.cpp
+++ b/lib/tdm_ripper.cpp
@@ -106,6 +106,27 @@ void tdm_ripper::parse_structure()
         group_id_.push_back(anode.attribute("id").value());
         group_name_.push_back(anode.child_value("name"));
         num_channels_group_.push_back(numchann);
+
+        // get time-stamp
+        pugi::xml_node insatt = anode.child("instance_attributes");
+        std::pair<std::string,std::string> startstop;
+        for ( pugi::xml_node bnode: insatt.children() )
+        {
+          assert( std::string(bnode.name()).compare("double_attribute") == 0 );
+          if ( std::string(bnode.attribute("name").value()).compare("Starttime") == 0 )
+          {
+            startstop.first = bnode.child_value();
+          }
+          else if ( std::string(bnode.attribute("name").value()).compare("Stoptime") == 0 )
+          {
+            startstop.second = bnode.child_value();
+          }
+          else
+          {
+            assert ( false && "unexpected attribute name" );
+          }
+        }
+        group_timestamp_.push_back(startstop);
       }
       if ( numchann == 0 ) num_empty_groups_++;
     }
@@ -289,8 +310,10 @@ void tdm_ripper::list_groups(std::ostream& gout, int width, int maxshow)
   gout<<std::setw(width)<<"group id";
   gout<<std::setw(width)<<"group name";
   gout<<std::setw(width)<<"num channels";
+  gout<<std::setw(2*width)<<"start time";
+  gout<<std::setw(2*width)<<"stop time";
   gout<<"\n";
-  gout<<std::setfill('-')<<std::setw(4*width+1)<<"\n";
+  gout<<std::setfill('-')<<std::setw(8*width+1)<<"\n";
   gout<<std::setfill(' ');
 
   for ( int i = 0; i < num_groups_ && i < maxshow; i++ )
@@ -299,6 +322,8 @@ void tdm_ripper::list_groups(std::ostream& gout, int width, int maxshow)
     gout<<std::setw(width)<<group_id_[i];
     gout<<std::setw(width)<<group_name_[i];
     gout<<std::setw(width)<<num_channels_group_[i];
+    gout<<std::setw(2*width)<<time_stamp(i,true);
+    gout<<std::setw(2*width)<<time_stamp(i,false);
     gout<<"\n";
   }
   gout<<"\n\n";
@@ -311,6 +336,8 @@ void tdm_ripper::list_groups(std::ostream& gout, int width, int maxshow)
       gout<<std::setw(width)<<group_id_[i];
       gout<<std::setw(width)<<group_name_[i];
       gout<<std::setw(width)<<num_channels_group_[i];
+      gout<<std::setw(2*width)<<time_stamp(i,true);
+      gout<<std::setw(2*width)<<time_stamp(i,false);
       gout<<"\n";
     }
     gout<<"\n\n";
diff --git a/lib/tdm_ripper.hpp b/lib/tdm_ripper.hpp
index 1f4a8cb..dee8d85 100644
--- a/lib/tdm_ripper.hpp
+++ b/lib/tdm_ripper.hpp
@@ -32,10 +32,10 @@ class tdm_ripper
   int num_channels_, num_groups_;
   std::vector<std::string> channel_id_, inc_id_, units_, channel_name_;
   std::vector<std::string> group_id_, group_name_;
+  std::vector<std::pair<std::string,std::string>> group_timestamp_;
   std::vector<int> num_channels_group_;
   std::vector<int> channels_group_;
   std::vector<int> channel_ext_;
-  // evtl. get group time_stamp of .tdm file in the unix format, i.e. #seconds since 01.01.0000 with average year having 365+97/400 = 365.2425 days
 
   // minimum/maximum value in particular channel (is provided in .tdm file as float)
   std::vector<std::pair<double,double>> minmax_;
@@ -248,6 +248,52 @@ public:
     }
   }
 
+  // evtl. get group time_stamp of .tdm file given in unix format
+  std::string unix_timestamp(std::string unixts)
+  {
+    // average year of Gregorian calender
+    const double avgdaysofyear = 365 + 1./4 - 1./100 + 1./400;
+
+    // std::tm epochStart = {};
+    // epochStart.tm_sec = 0;
+    // epochStart.tm_min = 0;
+    // epochStart.tm_hour = 0;
+    // epochStart.tm_mday = 1;
+    // epochStart.tm_mon = 0;
+    // epochStart.tm_year = 2040;
+    // epochStart.tm_wday = 0;
+    // epochStart.tm_yday = 0;
+    // epochStart.tm_isdst = -1;
+    // std::time_t epochtst = std::mktime(&epochStart);
+
+    // convert string to long int = number of second since 0000/01/01 00:00
+    long int ts = atol(unixts.c_str());
+
+    // int year = (int)floor((double)ts/(avgdaysofyear*86400));
+    // int month = (int)floor((ts-year*avgdaysofyear*86400)/(30*86400));
+    // int day = (int)floor((ts-year*avgdaysofyear*86400-month*30*86400)/86400);
+    // int daysec = ts-year*avgdaysofyear*86400-month*30*86400-day*86400;
+    // int hour = (int)floor(daysec/3600.);
+    // int mins = (int)floor((daysec-hour*3600)/60.);
+    // int secs = (int)floor((daysec-hour*3600-mins*60));
+
+    // return std::to_string(year)+"-"+std::to_string(month)+"-"+std::to_string(day)
+    //  +"  "+std::to_string(hour)+":"+std::to_string(mins)+":"+std::to_string(secs);
+
+    // use STL to convert timestamp
+    // std::time_t tstime = std::time_t(ts)-epochtst;
+    std::time_t tstime = ts - 1970*avgdaysofyear*86400;
+    return std::ctime(&tstime);
+  }
+
+  std::string time_stamp(int groupid, bool startstop = true)
+  {
+    assert( groupid >= 0 && groupid < num_groups_ );
+
+    return startstop ? unix_timestamp(group_timestamp_[groupid].first)
+                     : unix_timestamp(group_timestamp_[groupid].second);
+  }
+
   void list_datatypes();
 
   // convert array of chars to single integer or floating point double