Various concentrations of inorganic particles of volcanic ashes (VA) were added using twin screw extruder and the injection molding machines to the poly(vinyl chloride) (PVC) to fabricate PVC/VA composites. The effect of volcanic ash particles weight content (0, 5, 10, 15, 20, and 25 wt.%) on the mechanical properties of PVC/VA composites was investigated by tensile and flexural tests. Tensile and flexural properties of composite samples were determined under three different temperatures (-10 degrees C, 20 degrees C and 50 degrees C) by using Shimadzu AG-X test machine, having a load cell of 10 kN and equipped with the thermostatic chamber with controlled temperature environment. As a result, mechanical properties of PVC/VA composites showed that VA can be used as a filler material in PVC composites. Results of both, the tensile and the flexural tests showed that at -10 degrees C and at 20 degrees C, flexural and tensile strength values of 25 wt.% PVC/VA composites have decreased by nearly 15%, compared to value of pure PVC. Even though VA particles decrease the flexural and tensile strength of PVC, VA can be used as a filler material in PVC matrix. Morphologies of the fracture surfaces and the dispersion of VA particles were observed by using scanning electron microscopy (SEM).