To attain zero carbon emissions and mitigate carbon imprint on the environment, Ammonia is gaining traction as a promising alternative fuel to replace hydrocarbon fuels. However, the combustion characteristics of ammonia as fuel in a combustion system need to be investigated and examined. The aim of the current study is to analyse the laminar flame speed, a fundamental physio-chemical property of any combustible mixture, by means of experimental measurements and kinetic reaction mechanism analysis. Dealing with kinetic mechanisms can reveal the chemistry behind the reaction kinetics, which in turn can be used to analyse and improve the characteristics of ammonia as a fuel. The current study involved a series of experiments using the spherical expanding flame setup to measure the laminar flame speed of 70/30 (%vol) NH3/H2 at atmospheric pressure and ambient temperature across a wide range of equivalence ratios (0.6-1.4). The study also included analysing 36 kinetic reaction mechanisms in order to appraise their performance with respect to laminar flame speed prediction for the measured NH3/H2 mixture. Absolute percentage error (APE) formula has been adopted for preliminary estimation based on the experimental measurements of the present study and numerical data. The study found that Duynslaegher et al., 2012 kinetic model shows good performance in the prediction of laminar flame speed across lean and stoichiometry conditions with a minimum value of APE in the range 0%-6%. The mechanism of Nakamura et al., 2017 demonstrates good estimation of laminar flame speed under rich conditions as well as that of Gotama et al., 2022. The sensitivity analysis of the laminar flame speed revealed the most important kinetic reactions in the promotion and retarding the laminar flame speed of 70/30 (%vol) NH3/H2 mixture. The kinetic reactions of H+O2=O+OH, NH2+NH2=N2H2+H2, and OH+H2=H+H2O are the most important reaction with considerable effect in promoting the laminar flame speed at all conditions, while the reactions of H+O2(+M)=HO2+M, NH2+H=NH+H2, and NH2+O=HNO+H play an important role in the retarding of laminar flame speed from lean to rich conditions. The effect of the aforementioned reactions varies with respect to the equivalence ratio, mainly due to changes in adiabatic flame temperature.