Nonisothermal crystallization behavior of model ecocomposites based on polypropylene (PP), maleic anhydride modified polypropylene (PPm), and kenaf fibers were extensively studied. Melting and crystallization behavior of the composites with 20 wt/wt% kenaf fibers were analyzed by differential scanning calorimetry (DSC) in dynamic regime (with heating rate of 10 K/min, and cooling rates of 5, 10, 15, 20, and 40 K/min). It was shown that the kenaf fiber surface acts as a nucleating agent during nonisothermal crystallization of both PP matrices, shifting the onset and peak crystallization temperatures toward higher values. Crystallization behavior was analyzed by Avrami, Jeziorny, Ozawa, Mo, and Kissinger methods. The results confirmed the applicability of the used models, with exception of the Ozawa approach that was rather inapplicable for these composites.