A new adiabatic burner allowing the measurement of burning velocities at high pressure with the heat flux method has been developed. Experimental measurements of laminar burning velocities of methane and n-pentane were performed for pressures up to 6 atm at 298 K and at atmospheric pressure for temperatures from 298 to 398 K. Equivalence ratios varied from 0.6 to 1.9. The results for methane flames are in good agreement with the only results of literature obtained above atmospheric pressure using the heat flux method; those for n-pentane are to our knowledge the first application of this method to a flame of a liquid fuel above atmospheric pressure. Based on these measurements, empirical correlations of the variation of the measured laminar flame velocities with pressure and temperature have been proposed for methane and n-pentane. In the case of methane, these correlations lead to a satisfactory prediction of literature measurements made using constant volume bombs.