The present work is an experimental investigation into the plume axial temperature profile of hydrocarbon pool fires from axisymmetrical to linear-source geometry in normal (100 kPa) and sub-atmospheric (64 kPa) pressures. Five rectangular pool with the same area S (36 cm(2)) but different aspect ratios (long side divided by short side n = L/W = 1, 2, 3, 4, 8) are used. The plume axial temperature rise of the pool fire at a given height was observed to be higher in the reduced pressure than that in the normal pressure atmosphere. With the increase in pool dimension aspect ratio, the temperature power scaling law (Delta T similar to z(beta)) decay index (beta) transits from -5/3 (axisymmetric source) to -1 (line source). An exponential function is proposed to characterize such transition behavior in relation to the source aspect ratio of the pool fire, which is shown to be well verified by the experiments. A global model, with both ambient pressure and pool dimension aspect ratio accounted for, is then developed for the plume axial temperature profile of rectangular hydrocarbon pool fires. (C) 2014 Elsevier Ltd. All rights reserved.