We plan to take the train, Krakow to Warsaw in late May. On a Monday. Wondering if those trains sell out...like Amtrak sometimes does.

S0...should we make arrangements on one of the websites ahead of time to be sure of availability, or is it safe to wait until we are in Krakow? We will want to leave on a specific day, not necessarily a specific time.

Dziekuje!

2nd class could sell out I suppose but rarely first class and there are so many trains - check www.bahn.de/en - the German Rail site to see how many trains there are. Or if you know the exact train you will take book online on the Polish Railways site - full-fare tickets are generally changeable but if a discount generally train-specific and non-refundable - as a rule of thumb on European trains in general. I am not expert on Polish trains but present the general rules in most countries.
Hopefully someone with more precise knowledge of Polish trains will answer or look at these superb IMO sites for info on European and Polish trains - www.seat61.com may have the most up-to-date info on Poland or try www.ricksteves.com or www.budgeteuropetravel.com - if wanting to pay a bit more and have a secure booking try the latter two - agents of RailEurope whose tickets are generally full-fare tickets but a surcharge is added on - as a last resort if you can't go right thru the Polish Railways - think Man in Seat 61 recommends some Polish travel agency but not sure.

I don't think that train would sell out. I took Warsaw-Krakow last July, and we bought them on Polrail ahead of time, I think. Now I'd probably just buy the tickets in Krakow if I had some flexibility. Definitely check the schedules, though, so you have some idea of when the trains you may want to take are departing. I'd buy them a day or two ahead, but I'm sort of panicky about train tickets.

I would buy the tickets when you get to Krakow. The train station is about a 10 minute walk from Rynek Glowny. I found that first class was quite full with business travelers so I would make a seat reservation when you buy the tickets.

according to www.bahn.de - German Rail site I always use for schedules for its simplicity there are trains Krakow to Warsaw every hour or every two hours throughout the day - all seem to require advance seat reservations so I would do that as soon as I reached Krakow - but so many trains to chose from I would not worry that much about this.