Laminar flame speeds of hydrogen blended n-butane flames at atmospheric pressure and room temperature was measured in a combustion vessel with Schlieren photography, and determined using nonlinear regression analysis. According to the hydrogen addition parameter (RH) and effective equivalence ratio (φF) defined by Yu et al (1986), laminar flame speeds (Suo) for φF between 0.6 and 1.4 were found to increase linearly with RH from 0 to 0.5, with the slope of the variation assuming a minimum around stoichiometry. These experimental results correlate well with computed laminar flame speeds using the detailed reaction mechanism, USC Mech II. Furthermore, the adiabatic flame temperature was found to also increase monotonously with RH at specific φF, with the extent of the increase being the smallest around stoichiometry. It is therefore suggested that the effect of hydrogen addition on the laminar flame speeds of n-butane flames can be satisfactorily correlated with the response of the corresponding adiabatic flame temperature.