The disposal of Sewage sludge is one of the serious problems faces the world today. This Sewage sludge contains large concentration of organic substance, pathogens content and has high pollutant effects. This study is concerned with improving anaerobic sludge digester performance by co-digesting sewage sludge and other organic wastes. Molasses, Wheat straw, rice husk and rice straw checked and evaluated. A bench scale erected for this reason in El Berka wastewater treatment plant in El Sallam district, Cairo, Egypt. The experimented sludge was thickened sludge. The experiment consists of four stages. In the first stage molasses, rice husk and wheat straw were added to sewage-thickened sludge (TS) at mixing rates 5%, 10% and 15% by weight. In the second stage, the molasses was added to sewagethickened sludge at 5%, 10%, 15%, 20% and 25% by weight. In the third stage mixture of agriculture residues Molasses + Rice husk and Molasses+ wheat straw added to sewage sludge at 15% mixing rate. In the fourth stage Molasses, wheat straw and mixture of Molasses+ wheat straw added to sewage sludge at 15% mixing rate by weight. Characteristics of thickened sludge such as Temperature, pH, COD, TS, VSS, total alkalinity, volume of methane and CBOD/NBOD ratio were monitored and evaluated. The most efficient material based on COD, BOD and VSS destruction percent evaluated and the results showed that co-digesting sludge with 15% mixing rate (7.5% molasses +7.5 % wheat straw) gives best results with respect to effluent BOD and COD.