Madrid to Barcelona by rail

Have you tried the Renfe website?

http://www.renfe.com/EN/viajeros/horarios.html

Renfe is the place to go. Click Welcome on the upper right to change the site to English, then put in your dates, etc. Choose Madrid - Puerta de Atocha and Barcelona - Sants as your two stations. When you get ready to book, it helps if you register with the site before actually attempting the purchase. The system will ask you to register your credit card with Verified by Visa, but you can do that during the process. You will also select your seats during the purchase. The sooner you book, the more likely you are to get great prices. I was told to book about 45 days ahead for promo fares, but I started checking at about 60 days, and found one for 37 euro. I was going the other direction (Barcelona-Madrid), but it left at 1:05 and got into Madrid at 3:45.

If over 60, you can get a rail discount card, that gives a 25 or 40% discount on walk up fares.

The AVE train from Madrid to Barcelona takes 2.75 hours ( a few trains take 3.0) and they leave nearly hourly. Full fare is 106 euros but you can get a Promo fare as little as 32 euros if you buy about two months in advance. To see the Promo fares, gomtomthe "purchase" area on Renfe.com, not the Fares and Schedules area. And make sure you don't get switched toRailEurope. If you Google Renfe, it should be the top one.

Many report that the RENFE site is difficult to use; if you need help, try this extensive tutorial from TripAdvisor.