Experimental results of free convective heat transfer on a round plate with additional elements on the surface at ambient air temperatures are presented. The tests were performed at horizontal and vertical positions of the plate. The influence of an annular non-heated barrier and partial upper insulation was studied. Experimental data were obtained at steady-state and transient modes over the Rayleigh number range from 1 x 10(7) to 2 x 10(8). Validity of the quasi-steady-state postulation for transient heat transfer was evaluated. Results were reduced to power-type relations Nu = f(Ra) and compared with tile known steady-state data for free convection over smooth surfaces.