In this study, a gas-liquid-solid microreactor with the polydopamine functionalized surface coated by highly-active palladium nanocatalysts using the electroless deposition was successfully developed for hydrogenation of nitrobenzene. Experimental results showed that in the 40-h continuous operation, the developed microreactor exhibited rather high average nitrobenzene conversion more than 97% under various inlet nitrobenzene concentrations from 30 to 90 mM. Besides, the effect of the gas and liquid flow rates on the aniline concentration and nitrobenzene conversion was also studied. It was found that for a given liquid flow rate, the increase of the gas flow rate led to an increase in both the aniline concentration and nitrobenzene conversion as a result of more hydrogen supplied. Further increasing the gas flow rate caused no change of them due to excess supplied hydrogen. There existed a minimum gas flow rate to acquire the complete conversion of nitrobenzene. Similarly, for a given gas flow rate, increasing the liquid flow rate did not change the aniline concentration and nitrobenzene conversion due to sufficient supply of hydrogen. Once the supplied hydrogen became insufficient at high liquid flow rate, both the aniline concentration and nitrobenzene conversion were decreased. Based on these results, the excess ratios were achieved under different conditions. It was found that the excess ratio decreased with the increase of the liquid flow rate and inlet nitrobenzene concentration as a result of the enhanced mass transport. The obtained results in this work are beneficial for optimizing the gas-liquid-solid microreactor operation. (C) 2016 Elsevier B.V. All rights reserved.