A facile synthetic procedure for N-doped ZnO powders was proposed. In this work, N-doped ZnO crystals were synthesized in diethylene glycol (DEG) with ammonia solution via solvothermal process. Incorporated N concentration increases with the amount of ammonia solution. In order to confirm the defects of as-gained ZnO powders, the samples were characterized by XRD, PL,and EPR. In our results, the N-related defects were considered to be (N-center dot)(O) centers as acceptors, other than (N-2)(O). And, the donors defects were confirmed to H-i. UV photocatalytic activity of the N-doped ZnO crystals was assessed from the photodegradation kinetics of methyl orange (MO). The result shows that the UV photocatalytic activity of N-doped ZnO decreases with the incorporated N concentration. This was caused by abundant acceptors hindered the photoinduced holes generating. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.