This study compared the performance of anaerobic digestion (AD) of municipal solid waste under 101 kPa (R system) and 65.8 kPa (RPC system) - the atmospheric pressure on the Qinghai-Tibetan Plateau, China. Gas production, gas composition, degradation of volatile solids, pH, alkalinity, volatile fatty acids, and ammonia concentration were analyzed to examine how the two systems responded to change in the organic loading rate. The RPC system had a stronger buffering capacity and lower gas production rate and could achieve a higher loading rate. The pH in RPC recovered more rapidly in the starting stage and remained higher than that in R during the whole experiment, with an average difference of 0.2. During days 38-55, 56-70, and 71-125, the average methane production rates were 380.16, 318.67, and 402.21 L kg(-1) VS in R and 367.40, 299.04, and 275.06 L kg(-1) VS in RPC, respectively. (C) 2010 Elsevier Ltd. All rights reserved.