To overcome the problem of rapid depletion of natural energy reserves and consequent pollution caused by them, this work explored the possibility of utilizing sewage sludge biomass to produce bio-oil using hydrothermal liquefaction (HTL) pathway. In this study, effect of different reaction parameters such as reaction temperature, residence time, and sludge-to-water (ss-to-water) ratio on solid biomass conversion and bio-yield and its higher heating value (HHV) were investigated. Although maximum conversion of (99.7 %) and highest bio-oil yield (22.01 wt%) was achieved at 330°C, however optimum temperature was chosen as 300°C which produced conversion efficiency and yield of bio-oil very close (98.07 % and 21.5 wt% respectively) to what was obtained at 330°C as lower temperature is beneficial for overall economy of the process. Similarly, a residence time of 60 min and ss-to-water ratio of 1:6 was screened to be producing optimized yield of bio-oil. HHV of different fractions bio-oil was much improved (30.18 MJ kg-1 of acetone phase and 38.04 MJ kg-1of DCM phase) as compared to that of raw feedstock (12.74 MJ kg-1). Carbon balance performed on the products indicated that maximum amount of carbon went to bio-oil phase (53.4 wt%). However, a significant portion of carbon was lost (33.9 wt%) due to the limitation of experiments at lab scale which involves evaporation and drying to reach final products. FTIR spectral analysis of different bio-oil phases showed that it was mainly made up of alcohols, alkane, ketones, aldehydes and carboxylic acids.