The study of hydrogen combustion is relevant to the development of a hydrogen energy economy and safety in many industries. Lean hydrogen-air mixtures are characterized by cellular flame fronts which induce an increase of the propagation speed and of the energy release rate. The propensity of a mixture to develop such instabilities is estimated through the Markstein length. The purpose of the present study is to evaluate different method’s ability to predict this parameter for hydrogen-air and hydrogen-nitrous oxide mixtures. Two methods to predict the Markstein length have been employed: (i) a theoretical expres- sion from Matalon and (ii) cylindrical flame numerical simulations. The systems chemical dynamics were described using recent detailed reaction models. Experimental Markstein lengths from the literature have been selected to estimate the accuracy of both methods. The theoretical expression of Matalon proved able to predict relatively accurate Markstein lengths for H2-air mixtures but not for H2-N2O-Ar mixtures. The numerical simulations give reason- ably accurate values of the Markstein lengths for all mixtures. Also, the applicability of the numerical method extends to much wider ranges of conditions compared to the theoretical method.