[en] A new composition for the purification of strontium titanate monocrystal surface after mechanical treatment is suggested. The invention can be used in the process of production of nonlinear condensers (NC), operating at cryogenic temperatures. The invention is aimed at the elimination of pickling over crystallographic planes. The new composition contains additionally syntanol and as an acid - orthophosphoric acid. It is shown, that the use of the composition suggested permits to produce condensers with high dielectric properties. The composition suggested is harmless, not inflammable and does not produce a pickling effect on plane (111) of strontium titanate monocrystals