What train do you take from Barcelona to Monte Carlo?
Are you asking if there is a single train? Go to bahn.de for the schedule. Probably involve at least one if not two train changes.
Paula I think you will have to take a train to Nice then train to Monaco. Or have you looked at flying, Barcelona to Nice is like 50 minutes and can be dirt cheap we did it for 40 euros last summer.. You can then train or bus to Monte Carlo easily.
The only reasonable train connection is at 9:05 with a change at the border at Figueres Vilafant to change gauge onto a TGV, and then onto a second TGV at Valence, straight through then to Nice, changing there onto a local regional train to arrive in Monaco-Monte-Carlo at 18:47. The trip takes 9 hours and 42 minutes. Flying may be a better option unless you want the train journey, or unless you are using a Global Pass. Remember the mandatory (capacity controlled) pass-holder surcharge on each leg of TGV travel and because they are rare you need to see to that well in advance and they are not easy to change.
Do as Pat suggests. Fly easyJet from Barcelona to Nice. Book now to get a very cheap fare. Take express bus 110 directly from the airport to Monaco. The bus runs every 30 minutes.