Thermal properties of foundry sand determine to a great extent the rate of heat extraction from castings and thus influence their quality. Thermal properties of interest of C02 silicate molds are thermal conductivity, specific heat, heat accumulation factor and thermal diffusivity. The effect of variation of % of sodium silicate, gassing time and ramming strokes on aforementioned thermal properties of foundry sand have been reported. To know the independent, interactive and higher order effects of process parameters on the yield, experiments were planned according to central composite rotatable design with half replicate. The adequacy of the model was tested using analysis of variance and accuracy by experimental data. Finally, it has been concluded that such studies would be helpful to control the properties of molds/cores and thereby the quality of castings.