Chemically treated jute fabric (TJF)- and untreated jute fabric (UJF)-reinforced isotactic polypropylene (PP)-sandwiched composites, such as TJF composite (TC) and UJF composite (UC), with different JF contents (35-60 wt%) were fabricated by the compression molding technique. Then, PP, UC and TC were irradiated by gamma-rays with various doses (0-7.5 kGy) to produce gamma PP, gamma UC and gamma TC, respectively. Water intake (WI), chemical texture, tensile strength (TS), flexural strength (FS), Young's modulus (Y) and thermal degradation temperatures (T (d)) of the samples were examined. Activation energy (E (a)) during thermal degradation has been estimated by Broido's theory. WI in TC, gamma UC and gamma TC is lower than that in UC, as accompanied by the change in interfacial textures between JF and PP. The TS, FS, Y, T (d) and E (a) values of UC, TC, gamma UC and gamma TC are found to lie in the ranges 52-61, 55-63, 440-710 MPa, 400-440 A degrees C and 280-340 kJ/mol, respectively. A relative estimation of physical and chemical crosslinking densities/junctions in the composites has been performed and the values have been analyzed by the rubber elasticity and polymer gel theories. The observed changes in physico-mechanical and thermal properties of the composites have been explained on the basis of crosslinking/bonding between JF and PP. Fourier transform infrared spectroscopy confirms the fiber-matrix interactions. A significant increase in Y and T (d) values demonstrates a development of strong and thermally more stable JF-reinforced PP composites in the present study.