Waste is a resource. Municipal solid waste management is a great concern in Sri Lanka due to high water content and heterogeneity of the waste. Composting is one of the important, cost effective methods of management of biological waste in developing countries. This study was performed to determine the optimum moisture range for effective composting, which can be maintained throughout the bio-oxidative phase of the composting process to accelerate the decomposition rate and eventually get a better compost product. Four wind row piles were set up with moisture contents adjusted to 60% ± 10% (Control) for five weeks, 40% ± 10% (Pile A), 60% ± 10% (Pile B) and 80% ± 10% (Pile C) for 8 weeks. Moisture content of the control pile was lowered to a value of 40%± 10% during the last three weeks while other piles were maintained within the experimental moisture ranges for the eight weeks of composting cycle. According to the temperature profiles of the piles, pile B showed the best temperature level for microorganisms. Other physico-chemical parameters were not significantly different between piles. Therefore, moisture content of pile B (60% ± 10%) was selected as the optimum moisture range for the bio-oxidative phase in the composting process. Unskilled labourers can maintain that moisture level easily by performing the squeeze test for the moisture.