The laminar burning velocities of n-butane/air and isobutane/air mixtures have been determined over a range of equivalence ratios using the constant volume combustion bomb technique. By de-coupling the pressure and temperature, the dependency of the laminar burning velocity on the unburnt gas pressure has been determined experimentally for stoichiometric mixtures. Using the pressure dependency and original data, the temperature dependency was extracted. In addition, the effects of adding a simulated exhaust gas residual have been investigated for stoichiometric mixtures and the results presented. To minimise the effects of thermal buoyancy, the measurements were performed in a micro-gravity environment. This technique produces a spherical flame front and simplifies the subsequent analysis of the data. By retaining the spherical flame front it is possible to quantify the flame strain rate during the combustion event. The bulk of the data presented have been extrapolated back to datum conditions of 298 K and 1 bar (abs.). This allows the results obtained in the current study to be compared with results obtained with different measuring techniques and/or different fuels. Curve fits for the data are presented which allow the laminar burning velocity of these two fuels to be determined over a range of equivalence ratios (0.7 to 1.5), unburnt gas pressures and temperatures (0.5 to 3.0 bar and 298 to 420 K respectively), and exhaust gas dilution (up to 15% by vol.).