[en] Many world wide experimental facilities like SLAC, PEP-II, BABAR, BELLE, CLEO, ARGUS provide rich data on the charged open flavoured mesons. The leptonic decays of these open flavour charged mesons are really a challenge to the experimentalists. For example, in the case of B⁺ → τ⁺ν_τ, the τ lifetime is very short so it decays very rapidly producing additional neutrinos. As these neutrinos belongs to the neutral lepton class they interact via weak interactions only. To supplement the experimental effort theoretical estimations of such decay processes become relevant. In the present paper, the theoretically calculated branching ratio for the leptonic decays of the charged meson systems such as D⁺_S, D⁺, B⁺ and K⁺ are given