The topic of waste incineration/co-incineration is critical, given the increasingly stringent regulations on environmental aspects. The widespread use of polymeric materials generates significant waste, posing an ecological problem. Current regulations mandate a reduction in the landfilling of plastic waste, which should be replaced by recycling, with the possi-bility of exploiting the energy potential due to its high calorific value. The electricity generation in Poland is mainly based on coal, so using polymers as alternative fuels is an important research issue. The research results presented in this paper make it possible to compare the properties of selected waste plastics and coal and their behavior during thermal processes, considering the quality of the gases released. Based on the thermal analyses, a FuzzyTherm model was introduced based on one of the fuzzy logic methods, one of the main artificial intelligence modeling approaches. The model predicts the temperatures corresponding to endothermic and exothermic reactions. The model achieved good accuracy. The maximum relative error between measured and calculated data is lower than 11%. These aspects constitute an innovative element of this paper.