Python datetime – setting fixed hour and minute after using strptime to get day,month,year

Use datetime.replace:

from datetime import datetime
dt = datetime.strptime('26 Sep 2012', '%d %b %Y')
newdatetime = dt.replace(hour=11, minute=59)

Also worth noting: datetime.replace returns a new copy of the datetime (since datetime is immutable): it is like str.replace in that regard.