The objective of this work was to study the effect of silica (SiO 2) and calcium carbonate (CaCO3) on compounding torque, mechanical, physical and morphological properties of cellular natural rubbers, using a conventional vulcanisation (CV). The cure temperature and time being 160°C and 7 mins respectively with oxybisbenzenesulphonylhydrazine (OBSH) as a blowing agent. The results indicated that addition of 20 phr SiO 2 in the rubber compound was the most preferable for the tensile strength, which also promoted the swelling resistance in toluene during equilibrium state. In the case of CaCO3 filler, added into the rubber compounds with 20 phr SiO2, the optimum CaCO3 content to maintain the required properties was between 20 and 30 phr. The CaCO3 above 30 phr reduced the tensile strength of the compounds due to the excessive silica and calcium carbonate contents being greater than 50 phr. In summary/the recommended mixed fillers contents for SiO2 and CaCO3 in this work were 20 phr and 20 - 30 phr, respectively.