To reduce the organic fraction of tannery primary sludge, which is classified as hazardous waste in India, batch anaerobic digestion was done at 10% solids concentration in non-mixing condition and at room temperature (28°C to 40°C). To enhance the rate of sludge hydrolysis during anaerobic digestion, the various pre-Treatments like autoclaving, thermal treatment, alkali treatment, and biological sulphate reduction were done. Evaluation of the pre-Treatments indicates that thermal pre-Treatment of the sludge at a temperature of 170°C for 60 minutes enhanced the anaerobic digestion with an increased methane yield (50%) and was the best pre-Treatment. Further, optimisation of pH and COD/VSS ratio of the feed, enhanced anaerobic sludge digestion and resulted in approximately 50% removals of soluble COD and VSS. The results presented in this study can help to choose the best pre-Treatment route for effective anaerobic digestion of hazardous primary sludge prior to its disposal in landfills. © 2016 Inderscience Enterprises Ltd.