I'm asking for my Thai husband, who's lost his current passport (which may have expired anyways), but has his old passport. Anyone know if it would be easy to obtain a new one for him? We live in Chiang Mai. Thanks

He probably will need a police report of the lost passport.

For the rest he can apply at the Chinag Mai Provincial hall just outside CM, ground floor. Doesn't take long, cost 1,000 baht. For 40 baht extra they will send it by EMS to his home, usually takes no longer than 5 days.

This would be better in the Thailand forum.

What to do when you lose your Passport?

• Lost/stolen domestically: must file a police report then bring that report to apply for a new e-Passport and cancel the misplaced Passport.

From: http://www.mfa.go.th/main/en/services/1415/21480-Passport-Amendments-Pages-Appending--Cancellatio.html

If the passport is expired a police report might not be required. (But would be wise to do anyway, as it could have been used for illegal activities if stolen)