This work presents the lattice Boltzmann simulation of natural convection in an open ended square cavity subjected to partial heating. The size of heater is half of characteristic length and placed at middle location of one vertical wall. Numerical simulations are performed for three different fluids of industrial, scientific as well as domestic field, viz., air (. Pr = 0.71), dichloro-difluoro-methane (. Pr = 4.5) and water (. Pr = 7). The influence of the partial heater on heat and hydrodynamic characteristics of an open ended cavity have been elucidated. It is observed that isotherms become more confined toward the partially heated portion of wall with the increase in Prandtl number. The heat transfer rate shows linear increase with the Prandtl number, i.e., enclosure containing water shows higher heat transfer rate followed by R-12 refrigerant and air. The numerical results are summarized by the empirical correlation relating Nusselt number with Rayleigh and Prandtl numbers. © 2014 Taiwan Institute of Chemical Engineers.