Rayleigh-Benard natural convection of aqueous gadolinium nitrate solution (paramagnetic) was studied experimentally and numerically in the presence of upward magnetization, force in a framework similar to that proposed by Braithwaite et al. With the magnetic susceptibility of the gadolinium nitrate solution reevaluated by the Gouy method, the measured heat transfer rates were found to agree with Silveston's experimental curve, which represents the relationship between the Nusselt number (Nu) and the magnetic Rayleigh number (Ra-m). Furthermore, three-dimensional numerical computations were also carried out. Every convection, flow pattern became axisymmetric, and the computed Nu agreed with Silveston's curve when Ra-m was used in place of the Rayleigh number. (c) 2005 American Institute of Chemical Engineers