This research is focused on developing a process called nitrolysis for treatment of excess sludge from wastewater processing. In this process, the excess sludge is treated with nitric acid (up to 11 wt %) at an elevated temperature (>160 degreesC) and pressure (100 psig). The result of this treatment is a substantial conversion of the excess sludge to soluble organic. This conversion reduces the viscosity and solids content of the excess sludge stream, thus reducing the disposal costs. The products of the reaction include biodegradable organics that may be recycled to the wastewater treatment process. Other products include potentially recoverable organic acids such as acetic acid. These acids are produced at about 0.15 g/g of dry excess sludge that reacts. This study investigates the operating parameters that could improve the conversion of excess sludge to products and/or biodegradable soluble organics. The parameters used in this study included temperature, acid concentration, sludge concentration, and reaction time. An initial factorial study of these parameters indicated that the acid and sludge concentrations were the most influential in the conversion process. Increasing the acid concentration would convert more of the excess sludge to product. Although the initial study did not show a change in conversion above 160 degreesC, decreasing the temperature below 160 degreesC showed a significant decrease in the excess sludge conversion from 75% to 22%. The lower acid concentration also showed a significant drop in conversion, decreasing from >60% at 11.2 wt % acid to 10% at 0.4 wt % acid. Chemical oxygen demand and total organic carbon tests were used to verify the material balance around the reactor with better than 90% closure. These tests also demonstrated that the initial hydrolysis step in the biomass degradation is very rapid (<5 min).