For the first time, the history of the development of exploration geochemistry as a new technological direction of geological exploration is consistently described. M.P. Rusakov (1926) was the first to apply the method of geochemical prospecting based on ‘primary’ ore haloes in Kazakhstan. V.A. Sokolov developed (1929–1935) a method for gas surveying. The general concept of prospecting based on dispersion (‘secondary’) haloes and its practical implementation emerged in the period from 1932 to 1941 as a result of the work of a team of specialists led by N.I. Safronov, E.A. Sergeev, and A.P. Solovov.