The possibility of applying Weibull mixture model for the fitting of the nonisothermal kinetic conversion data has been investigated. It has been found that the kinetic conversion data at different heating rates can be successfully described by one or the linear combination of few Weibull distribution functions. Several simulated and real kinetic conversion traces have been analyzed. An optimal fitting of the kinetic conversion data has been obtained by a mixture of Weibull distribution functions. The results obtained have shown that the obtained conversion curves calculated by the model proposed in this paper are in agreement with the raw kinetic conversion data.