An experimental investigation on natural convection in air in vertical convergent channels with wall uniform heat flux is presented. Wall temperatures show that by increasing the spacing the effect of the convergence angle decreases. For the lowest spacing, a significant decrease of maximum wall temperature occurs passing from the parallel vertical plate configurations to convergence angles 0 >= 2 degrees. Dimensionless wall maximum temperature and Nusselt numbers are evaluated and correlated to the Rayleigh number or the channel Rayleigh number. The correlations are in the ranges 2.85 <= Ra'bmin <= 1.22 x 10(5) and 0 degrees <= 0 <= 10 degrees. Flow visualization is carried out both numerically and experimentally. Numerical and experimental data are compared and a good agreement has been found. (C) 2006 Elsevier Ltd. All rights reserved.