Recently, colossal research interests have been paid in the scienti c community to synthesize biomassbased polyols due to their availability, sustainability, and low toxicity. Here, in this work, the main objective involves an effective synthesis of bio-polyol from spent coffee ground through an acidcatalyzed liquefaction reaction by employing sulfuric acid and a mixed solvent of polyether polyol and glycerol at a reasonable reaction temperature. The effect of experimental liquefaction conditions on the extent of conversion was optimized by the design of experiments and statistical analysis using a 2 3 -fullfactorial design with temperature, time, and acid concentration as the process parameters. Also, the analysis of variance results with a 95% con dence level reveals that acid concentration is the most in uencing factor on biomass conversion. However, the achieved maximum conversion was 65.3 wt% at 170°C, 120 min, and 4 wt% of catalyst. The prepared polyol at the optimized condition showed an acid value of 18.6 mg KOH/g polyol, a hydroxyl value of 77.9 mg KOH/g polyol, and a viscosity of 348.2 cPs at 25 ºC. Thus, this work demonstrates a promising and e cient approach to synthesize bio-based liquid polyols using acid liquefaction at a reasonable temperature.