Stable zeolites are demanded in heterogeneous catalytic upgrading of water-containing feedstocks such as biomass and heavy oil. Herein, we report hydrophobic mordenite (MOR) via chemical liquid deposition (CLD). Prior to the surface treatment, pure MOR was synthesized with a Si/Al ratio of 15. The Si/Al ratio plays a crucial role in the synthesis of pure MOR phase. Surfaces of MOR crystals were treated with two different silane reagents and multiple-cycle treatments. Improved hydrophobic surface properties were observed for tetraethyl orthosilicate (TEOS) as compared with 3-aminopropyl triethoxysilane (3-APTS). The amount of silane compound deposited on the zeolite surface increased with an increase in the number of cycles. These findings are expected to stimulate the applications of hydrophobic zeolites in biomass and heavy oil conversion. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.