Previous studies on buoyancy driven pure convective motion in triangular enclosures have produced conflicting results in regards to the convective stability of the fluid. The purpose of this paper is to address many of the unexplained observations of previous studies as well as to provide validation of some of the earlier results. The time-dependent, two-dimensional vorticity transport and energy equations are solved numerically for a triangular enclosure having isothermal boundary conditions at the base and inclined surfaces by using the third-order accurate QUICK scheme. All previous studies had utilized schemes of second-order accuracy. The vorticity at the boundaries is computed by using second-order accurate, third degree polynomial approximation of Jensen’s type and the stream function equation is solved by successive overrelaxation. Results are presented for air as the convective fluid with Rayleigh numbers in the range of 7.1 × 102 to 7.1 × 105 while the aspect ratio of the enclosure varies from 0.2 to 1.0. Two types of flow configurations are investigated with the inclined surfaces considered hot for one and cold for the other. The paper discusses in detail the phenomena of cell bifurcation, cell detachment and reversal in cell rotation observed for fluids heated from the base. Numerical correlations are obtained for steady state values of Nusselt number as a function of Rayleigh number and aspect ratio.