The (111)-layered perovskite materials Ba5Ta4O15, Ba5Ta2Nb2O15 and Ba5Nb4O15 are prepared with nanofiber morphology via electrospinning for the first time. The nanofibers are built up from small single crystals, with up to several micrometers length even after calcination. The formation mechanism is investigated in detail, revealing an intermediate formation of amorphous barium carbonate strengthening the nanofiber morphology for high temperature treatment. All nanofiber compounds are able to generate hydrogen without any co-catalyst in photocatalytic reformation of methanol. After photodeposition of Rh-Cr2O3 co-catalysts, the nanofibers show better activity in overall water splitting compared to sol-gel-derived powders.