Transparent single crystalline BaTi2O5 was prepared by the floating zone (FZ) method. A large size single-crystalline BaTi2O5 rod, 5.5 mm in diameter and 30 mm in length, was prepared by masking the molten zone with Al foils in FZ. The growth direction was perpendicular to the (020) plane. The single crystalline BaTi2O5 rod had (002) facets parallel to the growth direction. The optical transmittance of single-crystalline BaTi2O5 was almost 100% in the visible region after post-annealing in air for 3.6 Its (C) 2013 Elsevier B.V. All rights reserved