The enhancement effect of compatible solutes on anammox activity under salinity stress was investigated. Glycine betaine (GB) was the most effective in alleviating salt toxicity, although all the compatible solutes (GB, trehalose and ectoine) were found to be valid. Acclimation potential of anammox biomass under salinity of 30 g/L increased significantly with GB addition. The recovery time in the reactor with GB addition (R-B) (49 days) accompanied by a more stable stoichiometric ratio was 2.65 times shorter than in the control reactor (R-C) (130 days). After 49 days, the extracellular polymeric substances and the tetrazolium chloride-dehydrogenase activity were 217.9 mg/gVSS and 38.7 mu g TF/gVSS/h in R-B, 1.86 times lower and 3.17 times higher than the levels in R-C, respectively. R-B possessed evident superiority in the aspects of microbial population proportion. And thus, compatible solutes addition was regarded as one of the feasible solution to counteract saline inhibition on anammox. (C) 2014 Elsevier Ltd. All rights reserved.