It is imperative to know the energy content of the char to ascertain its application, which is environmentally friendly and efficient. In this context, the higher heating values (HHV) of the char resulting from the co-cracking of residual fuel oil (RFO) with various other waste plastics have been determined experimentally. Experimental results of the proximate and ultimate analysis of the char obtained from the co-cracking process were used to estimate the higher heating values (HHV) using eight different correlation models. The char obtained from the co-cracking of RFO and polypropylene (PPI) was found to have higher heating values (HHV) of 31.02 MJ/kg, while the HHV of Bakelite (BL) showed 23.56MJ/kg. The best among the proximate correlations considered in this study resulted in the coefficient (R2) of 0.971, the average bias of ?0.68%, and absolute error of 1.70%. The most relevant among the ultimate correlation models resulted in the coefficient of determination (R2) of 0.980, whereas the average and absolute bias errors were found to be -1.29% and 0.25%, respectively. The proximate and ultimate analysis of the chars reveals a direct interaction between the reactive species during the co-cracking of RFO with various types of plastic waste used in the study.