The present work reports the measurement of the laminar burning velocity for n-propanol and air mixtures at 1 atm pressure, with the unbumt mixture temperature varying up to 620 K using externally heated mesoscale diverging channels. Planar flames were stabilized in quartz channels using an externally heated mesoscale diverging channel to create a positive temperature gradient along the direction of fluid flow. The laminar burning velocity was extracted using the mass conservation principle at the flame surface and channel inlet. The performance of six recent kinetic mechanisms was evaluated through a comparison of the predictions to present experimental results. A significant disagreement (approximate to 22%) was observed between different mechanism predictions, even at lower mixture temperatures of 335 K. The temperature exponent, alpha, was extracted using power-law correlations and observed to follow an inverted parabolic pattern with a minimum at a slightly rich equivalence ratio of 1.1, similar to other alcohol fuels.