The stimulating effect of humic acids on the growth of the biomass of the test object was established. А series of positive effects on the biomass of seedlings was proposed. The correlation dependence of the effect of toxicants on the cockweed on its composition was revealed. It was shown that the light ends of oil has a minimal toxic effect on cockweed due to increased volatility, in contrast to petroleum. The detoxifying ability of peat humic acids was established separately and together with oil-degrading microorganisms of the genus Rhodococcus on the inert substrate by the method of biotesting. Humic acids had a stimulating effect on the test object regardless of their genesis. The maximum stimulating effect on the test object was exhibited by humic acids isolated from fen peats. The biomass of cockweed seedlings on contaminated soil in the presence of humic acids and microorganisms of the genus Rhodococcus in all variants of experiments with model toxicants was higher compared to the variant without treatment with humic acids. The detoxification coefficients of humic acids were calculated separately and together with oil-degrading microorganisms of the genus Rhodococcus in the relation to hexadecane: the humic acids of sphagnum high-moor peat and sphagnum transitional peat showed the maximum detoxifying effect: 70−75%. Combined use of humic acids and microorganisms Rh. erythropolis S67, Rh. erythropolis X5 increased the detoxifying effect of humic acids by 4−22%. The values of the detoxification coefficients vary in the range of 59−85%, depending on the genesis of humic acids and the selected strain of microorganisms. The values of the detoxification coefficients of humic acids together with moil-degrading microorganisms of the genus Rhodococcus exceed the indicators of control and experimental options using only humic acids due to the ability of Rhodococcus to produce biologically active surfactants capable of more emulsification and biodegradation of oil hydrocarbons in the environment.