Natural convection and heat transfer in a vertical air slot partitioned by corrugated plates have been analyzed by the finite-element method to investigate the heat transfer characteristics as an insulating wall. The modified Galerkin method was used for the formulation. The computations were performed for the Prandtl number 0.7 in the Rayleigh number range from 103to 106. Two thermal boundary conditions were considered for the partition plate: the conduction case and the no-thickness case. In the case of no thickness, radiation heat flux was included in the heat balance on the partition plate. The radiation effect was examined for a wide range of emissivities. The heat transfer performance was compared with that for the flat partition plate case. Both convection and radiation heat transfer rates for the corrugated partition plate are less than those for the flat partition plate.