According to their documentation “Link below” to set their date time picker to military time you have to create a new culture. We are using the culture below, as you can see from the screen shot it got it half way right but I think it would be better without the AM & PM after it.I attached a screen shot of the clock. We just want to remove the AM and PM.
CultureInfo cultureInfo = new CultureInfo("en-US");
cultureInfo.DateTimeFormat.ShortTimePattern = "H:mm";
cultureInfo.DateTimeFormat.LongTimePattern = "H:mm";
cultureInfo.DateTimeFormat.PMDesignator = "";
cultureInfo.DateTimeFormat.AMDesignator = "";
http://www.telerik.com/help/wpf/raddatetimepicker-features-formatting.html