Bratislava is indeed a fine place for a day trip from Vienna. There is a regular rail service that takes about 1hr 15min each way for about 15 euro return. Bus services take a little longer and a similar price.

Thank you!

Hi,

And can you buy train tickets on the train station or do you have to book ahead online? 

Thanks, 

Kirsten

Your pass is your ticket. For some trains, you can book a reservation. For some others, a reservation is mandatory. You can generally book them at a station but for popular trains, it's advisable to book in advance and often that can be done online or by phone. For the best place to book, see this thread:

And this page:

https://www.seat61.com/interrail-and-eurail-reservations.htm

For any questions about booking a reservation, please mention route, date and departure time.

Vienna - Bratislava i recommend the special offer of ÖBB that includes a return Journey and Public transport within Bratislava :´) 

Thanks @rvdborgt and @seewulf 

I wasn’t planning to use a travel day for this short (not to op expensive) trip, so I will look into the tip from @seewulf