Hi All, I am trying to calculate difference(in seconds) between two date/times formatted as following: 2010-05-11 17:07:33 UTC 2010-05-11 17:07:33 EDT time1 = '2010-05-11 17:07:33 UTC' time2 = '2010-05-11 17:07:33 EDT' delta = time.mktime(time.strptime(time1,"%Y-%m-%d %H:%M:%S %Z"))-\ time.mktime(time.strptime(time2, "%Y-%m-%d %H:%M:%S %Z")) The problem I got is EDT is not recognized, the specific error is "ValueError: time data '2010-05-11 17:07:33 EDT' does not match format '%Y-%m-%d %H:%M:%S %Z'" Thanks,