A rigorous kinetic model for the formation of filamentous carbon on a nickel catalyst by methane cracking is derived. The experimental study was performed in an electrobalance unit. The temperature ranged from 773 to 823 K and the partial pressure of methane ranged from 1.5 to 10 bar. The mode of experimentation ensured that the rate of growth of the carbon filaments was always based upon the same number of filaments. A kinetic model is selected in which the abstraction of the first hydrogen atom from molecularly adsorbed methane is the rate-determining step. Based on the results of the parameter estimation, an energy diagram for the methane cracking is constructed.