Investigation of boiling in a square channel, which is filled partly with porous medium, is reported. Influence of major parameters such as porosity and extent of filling of the porous medium on heat transfer rate, vapour volume fraction, vapour generation rate and pressure drop are analyzed. A new solver utilizing the framework of open-source CFD code OpenFOAM is developed to investigate the problem. It is found that addition of porous medium increases fluid temperature, vapour volume fraction, heat transfer and vapour generation rate. It is also established that heat transfer increases on lowering the porosity of porous matrix, when the ratio of thickness of porous medium to channel height (Hp⁎) is greater than 0.4. In addition, heat transfer rate increases if the porosity increases for Hp⁎ < 0.4, but not significantly, as compared to the cases with Hp⁎ > 0.4. Moreover, there is an increase in pressure drop for an increase in thickness and a decrease in the porosity. It is also found that for two-phase heat transfer, the maximum Nusselt number is approximately 4.8 times higher than that for the single-phase heat transfer in the same channel.