Experimental investigations were carried out to determine the influence of cement-silica ratio on the moulding properties of Portland cement bonded sand. Test specimens, comprising silica sand and additives, namely wood flour and dextrin, as well as molasses, with varying cement to silica sand ratio (RCS), were prepared. The specimens were subjected to tests in accordance with American Foundrymen’s Society (AFS) standard procedure to determine properties such as bulk density, mould hardness, permeability, compression strength and shear strength. Findings revealed that RCS and additives have significant effects on all properties developed in the moulding sand. As RCS increases, the bulk density, mould hardness, green compression strength and shear strength increases while permeability and shatter index decreases. However, RCS of 0.105 gives suitable properties for moulding work meant for iron castings.