The effect of zinc sulfide (ZnS) nanoparticles in chlorinated styrene‐butadiene rubber (Cl‐SBR) was analyzed by X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM), Differential Scanning Calorimetry, and impedance analyzer. The cure time, mechanical properties, and solvent transport of petroleum fuels through the Cl‐SBR/ZnS nanocomposites at different temperatures were evaluated. XRD and SEM studies showed that ZnS nanoparticles were well‐placed in the polymeric structure of Cl‐SBR. The increased glass transition temperature of the composite with the loading of nanoparticles indicated the increased molecular rigidity. Rheometric torque, alternating current conductivity, dielectric property, tensile strength, tear resistance, modulus, hardness, abrasion resistance, heat build‐up, and compression set were increased with the loading of nanoparticles, however, cure and scorch time, elongation at break, and resilience were reduced with the loading of nanoparticles. The diffusion results have been explained in terms of the size of liquid molecules and the diffusion mechanism was found to follow the anomalous trend. The activation energy for diffusion, sorption and permeation process was evaluated. These activation energy parameters were increased with the size of the penetrant molecules and also with the loading of nanoparticles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46538.