Ukraine’s railway system is undergoing a major makeover at the moment and is currently evolving into modern user-friendly transport system that would live up to European standards.
Most intercity trains in Ukraine are cheap, quite comfortable and are an excellent way to travel around the country. There are basically three types of trains in Ukraine: suburban, regular speed trains and intercity express trains.

Suburban trains connect small towns and villages around a regional city, and are a good way to travel off-the-beaten track. Extremely cheap, they are not always the most comfortable and clean. Tickets for suburban trains are not available for on-line booking and should be purchased at the ticket offices at the local railway stations. Tickets for suburban trains are usually sold without assigned seats, so passengers choose seats as soon as they get into the carriage.
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Regular speed trains are most commonly used by locals. They connect major cities and towns in Ukraine. There are usually 3 classes of seats on these trains. 1st class (or «Sleeping Wagon» or simply «SW») is a soft sleeper cabin for 2 persons, mostly available on long haul train routes. 2nd class (or «coupe») is a soft sleeper cabin for 4 persons and 3rd class (or «platskart») is a hard seater common carriage.

 There are no separate cabins in 3rd class carriages. Four berths are located on one side of the carriage, while two other berths are located sideways.
If you are traveling on an overnight train, the price of the bed-linen and one hot drink is already included in the price of the ticket. You can also buy snacks and refreshments on board.

Intercity express trains are the newest and most welcome addition to the Ukrainian railway system. These trains take almost half the time than regular speed trains, but are currently serving only few destinations: Kyiv-Lviv - Truskavets, Kyiv-Kharkiv, Kyiv-Zaporizhja, Kyiv- Ternopil, Kyiv-Kryvyy Rih, Kyiv-Odesa. There are 2 classes of seats on express trains. 1st class offers more seating space for passengers, that’s about the only advantage. Travelers enjoy free WI-FI and personal sockets to charge their electronic devices on the way. The prices for express trains are comparably high. In case you are booking a return ticket you can get 10% to 20% discount. Rates also vary depending on the day of the week you are traveling: Friday, Saturday, Sunday and Monday are the most expensive days to travel on.

In 2012 Ukrainian Railways finally entered the Internet world and launched an English-version website, where you can buy all your train tickets with a credit card.
To do so, go to booking.uz.gov.ua, choose your language from the top menu, and follow the instructions. The steps are straightforward and clear, and most will be able to navigate them without an issue.
Once you buy the ticket online, you will receive an email with the copy of the e-ticket. Your e-ticket is a valid travel document. You can print it out and present on the boarding or you can save it in your phone or any other electronic device and the controller will scan the QR code at the boarding. You also have to have a valid ID at the boarding.

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You can only buy train tickets for trains within Ukraine. So if you want to take a train from Lviv to Budapest, you won’t be able to do so online. You will have to go to the train station and get it from the counter.