BACKGROUND: The food waste produced in small cities, rural areas and small communities often coexists with agroindustrial waste, such as livestock and poultry manure, which include high levels of uric acid (UA). This study investigated the influence of UA on the composting of food waste in an in-vessel system. RESULTS: Results showed that the performance of food waste composting was significantly different in systems with UA amendment and without UA amendment. Treatment with UA addition was the first to reach the thermophilic phase. More intensive mass reduction took place in the UA-amended treatments at an early stage. The variations of pH and O2 uptake were also correlated with the added UA. A decreasing trend in C/N ratio and a general increasing trend for NH4+-N concentration were observed when UA was added. CONCLUSIONS: The overall effect of UA can be assumed to be the sum of a large number of individual events with different mechanisms. Appropriate strategies could be applied to adjust the composting process, mediating both positive and negative effects of the coexistence of food waste and UA as well as manure. The results from this study may have important implications for composting technologies used to treat food waste. Copyright (c) 2012 Society of Chemical Industry