In Bahrain they use both the Gregorian and Islamic calendars in government transactions. Short dates are written in "Day/month/year" from; when writing in Arabic and English:
For Gregorian calendar: ١٦/١٢/٢٠١٣ميلادي or 16/12/2013.
For Islamic calendar: ١٠/١/١٤٣٤هجري
Long dates start with day, followed by month and ended with year:
For Gregorian calendar: ١٦/ديسمبر/٢٠١٣ميلادي or 16/Dec/2013.
For Islamic calendar: ١٠/محرم/١٤٣٤هجري
Time
Official time is indicated with the 12-hour clock system; however, a 24-hour clock system is also used. Bahrain is in the Asian time zone AST – UTC+03:00 Arabia standard time.
References
Date and time notation in Bahrain Wikipedia(Text) CC BY-SA