The effect of Si on the reaction between Al and Al‐2% Si films with the transition metal Ti in bilayer structures is studied by the resistivity measurements on samples isothermally annealed in the temperature range of 400–450 °C. The change in the resistivity of the structures is correlated to the rate of formation of an intermetallic compound TiAl3due to the interaction between Ti and Al. It is found that the reaction rate of the intermetallic compound formation is reduced by a factor of 3 for Ti/AlSi compared with the Ti/Al bilayer structures. The growth mechanism in both the cases is indicated to be diffusion limited. The activation energy for the Ti/AlSi increases to 2.2 eV from 1.7 eV for the Ti/Al structure.