A mathematical model is proposed for simulating transformation kinetics of solid-state reactions. The model known as logistic model and is sigmoidal in nature. It is based on a hypothesis that the rate of transformation, at any instant, is proportional to transformed and untransformed fraction; no other assumption is made. The model was applied to experimental and predicted data sets of different types of solid-state reactions. The fitting of the proposed model compared to that using JMAK model. The logistic model parameters are correlated well with the nature of transformation curves. Further, the model parameters are fitted with macroscopic variables that affect transformation kinetics, e.g. temperature and heating rate.