Experiments have been conducted in a low speed horizontal wind tunnel to study the interaction of radiation and conduction on mixed convective heat transfer from an upward facing horizontal flat plate in air. Differential interferometer has been used to measure local convective heat fluxes. It has been observed that interaction between surface radiation and convection is significant for a low thermal conductivity plate material. On the basis of the previous and current studies, it can be stated that the multi-mode interaction problem is an outcome of the nature of convective boundary layer. The interaction between different modes of heat transfer would remain similar irrespective of the nature of convection (free/mixed or forced). © Springer-Verlag 2012.