Skim latex serum (SLS) is high-strength wastewater generated from latex processing. Anaerobic treatment of SLS can be enhanced by reducing the sulfate content, which is an inhibitor in the biogas production system. This study investigates the effect of mixing time and rubber wood ash (RWA) loading on sulfate removal from SLS. The optimum sulfate removal efficiency of 42 % was achieved when 10 g/L of RWA was loaded for 10 min. The biogas production efficiency from both desulfated and raw SLS was investigated. The highest 306.36 m L-CH4/g-COD of methane production yield was achieved from desulfated SLS using RWA loading of 10 g/L (DSLS10), which is 16 % higher than the yield generated using raw SLS as a substrate. Moreover, hydrogen sulfide content in the biogas produced by desulfated SLS was two times lower than raw SLS. The results indicate removing sulfate from SLS using RWA before feeding to the anaerobic digestion enhanced biogas production yield and quality.