Diesel is extensively used in India, however, also contribute to pollution. In this study, important physico-chemical properties of different ternary blends of diesel, waste cooking oil (WCO) biodiesel and n-octanol, are evaluated. Diesel and D80+WCB20+nO20 blend have almost similar density, calorific value, cetane index and CFPP. However, blends have higher kinematic viscosity and flash point as compared to diesel. GC-MS test shows the presence of 51.3% saturated and 44.24% unsaturated fatty acids. FTIR analysis shows a strong peak of carbonyl band at 1741 cm(-1) which indicates the presence of biodiesel. Ternary blends are found to be a promising alternative to petroleum diesel.