timeFormat 1.1
Determines the time-text that will be displayed on each event.
String/View Option Hash, default:
{
  // for agendaWeek and agendaDay
  agenda: 'h:mm{ - h:mm}', // 5:00 - 6:30
  // for all other views
  '': 'h(:mm)t'            // 7p
}
A single format string will change the time-text for events in all views. A View Option Hash may be provided to target specific views (this is what the default does).
Uses formatDate/formatDates formatting rules. (The formatting rules were much different in versions before 1.3. See here)
Time-text will only be displayed for Event Objects that have allDay equal to false.
Here is an example of displaying all events in a 24-hour format:
$('#calendar').fullCalendar({
  events: [
    {
      title:  'My Event',
      start:   '2010-01-01T14:30:00',
      allDay: false
    }
    // other events here...
  ],
  timeFormat: 'H(:mm)' // uppercase H for 24-hour clock
});
A View Option Hash can only be provided in version 1.4 and later.