The Anaerobic Digestion Model 1 (ADM1) was applied to the anaerobic digestion process in an Upflow Anaerobic Sludge Blanket (UASB) reactor treating domestic wastewater. It was evaluated based on data from a 250 L pilot scale reactor. The wastewater influent degradable characteristics and Sludge Retention Time (SRT) were established by several trial and errors simulation to establish appropriate values for parameters not measured experimentally. The model was further verified against varying load experimental results to ensure its usefulness for a wide range of relevant loads. The best fit was obtained using 60 d SRT and parameters recommended for mesophilic conditions, with average experimental values within 10% of the simulated results. The model gave a good estimation of reality and could be applied for feasibility analysis, design and operation of full-scale small plants to be used in rural areas. Kathmandu University (KU) domestic wastewater treatment plant simulation was used as example of such. It showed that a reactor volume of about 4 m3 (6 h HRT) would give reasonable reactor performance with 1.7 m3/d biogas production.