Decide what type of train you want to take. From Sofia, you can choose express or commuter trains, both of which are available for booking in advance or on the day of travel. However, advance purchasing is suggested to ensure a seat.
Have your passport on hand when you book. You'll need to provide passenger information such as your passport numbers, duration of your stay and whether you have any necessary travel visas.
Book tickets online through the Rail Europe Web site (see Resources below). You can also book by phone at 1-888-382-RAIL. The journey will be inexpensive to moderately priced.
Book a train ticket in person at the Sofia Central Station ticketing office using Bulgarian lev or a credit card. The train station is located on Maria Luisa Blvd., just a few minutes from the city center.
Book your train travel through an agent at least 2 weeks in advance. An agent can also assist you with other reservations such as a hotel or rental car in Bucharest.