The first TGV from Toulouse to Barcelona leaves Matabiau to night at 20.24 (8.24pm) arriving there at 23.26, so just 3 hours. There are 4 en route stops at Carcassonne, Perpignan, Figueres and Gerona. Fares are from 39euros to 77 euros. After a night partying in Barcelona catch the return at 10.24 getting back to Toulouse at 13.31 (1.31pm).
SNCF say the train (operated by the Spanish railway) has 347 places and runs each night. The time knocks one hour off the previous journey and marks the first part in the joining Toulouse to the high speed network. The Paris line should be completed by 2024 and the Narbonne HSL by 2035.