Bio-aviation fuel was firstly synthesized by hydroprocessing castor oil in a continuous-flow fixed-bed microreactor with the main objective to obtain the high yield of aviation fuel and determine the elemental compositions of the product phases as well as the reaction mechanism. Highest aviation range alkane yields (91.6 wt%) were achieved with high isomer/n-alkane ratio (i/n) 4.4-7.2 over Ni supported on acidic zeolites. In addition, different fuel range alkanes can be obtained by adjusting the degree of hydrodeoxygenation (HDO) and hydrocracking. And the observations are rationalized by a set of reaction pathways for the various product phases. (C) 2015 Elsevier Ltd. All rights reserved.