Post offices in Kiev are normally open for 8 hours a day. The central post office of the city, located at 22 Kreschatik Street, works from 8 a.m. to 9 p.m., from Monday to Saturday, and is open from 9 a.m. to 7 p.m. on Sunday. Here one can send letters, buy postcard, use a fax machine or make international calls. In the central post office one can use International Express Mail service, which guarantees that your mail will be delivered to one of 36 countries within 3 or 4 days.
You can also use a variety of mail services provided by such companies as DHL Worldwide Express, Federal Express, Pony Express, TNT Express Worldwide and United Parcel Service. You can find addresses of these couriers in Kiev in the Print and Take section of this website.
Important to note that, according to customs regulations, one cannot send traveler's checks, personal checks, credit cards, cash and passports through the international mail to Ukraine. Such a mail can be forfeited by postal authorities.
To send a regular mail from Ukraine you should use Ukrainian postage stamps that can be purchased at any post office. Postage rates depend on a recipient country. Though this is a very cheap way to send a letter, it's not so convenient. The main disadvantage of sending a regular mail is that such a mail in Ukraine is really snail-like: your letter will go for about a couple of weeks, so it's advisable to use express mail services.