We have investigated mechanism off the hydrogen atom abstraction from H2S by triplet CrO3, MoO3 and WO3 by quantum chemical ub3lyp/lanl2dz method. Activation energy of the CrO3 + H2S, MoO3+H2S, WO3+H2S reactions were calculated as: 2.45 kcal/mol, 2.41 kcal/mol, 2.16 kcal/mol. These values were greater than in the corresponding ones in the singlet state.  Beside we have investigated the spin density distribution in the transition states all them calculated. Allocated spin density has said about spin density transition from one oxygen centre to sulfur atom. Transition have been uncompleted (because value sulfur’s spin density was equal 0.429, at the same time spin density on oxygen atom was of 0.631 in the case of the CrO3 + H2S reaction). Transition in the transition state has not led to great change in difference between HOMO and LUMO for all system studied. The mechanism of the reaction have been proposed.