Temperature is a key factor in the hydrothermal synthesis of MoS2 with high catalytic activity. In this paper, the effect of synthesis temperature (sTemp) and initial temperature (iTemp) was carefully investigated against catalyst crystal structure and hydrotreating activities. The synthesized nano-MoS2 was extensively characterized and evaluated using light cycle oil. There is a minimum sTemp for the formation of crystalline MoS2. Temperatures lower than the minimal sTemp result in amorphous structures. Surpassing this temperature leads to crystallization which goes through different growth routes. Higher iTemp promotes fast nucleation and thus nuclei combination growth. This leads to shorter slabs with a larger degree of defects, and a higher hydrotreating activity. At lower iTemp, crystal tends to grow in a continous way, resulting in fewer defects. In this way, with the increased sTemp, crystallinity is enhanced and slabs are curved and shortened. Both effects lead to improved hydrotreating performances. (C) 2014 Elsevier B.V All rights reserved.