Abstract <p>Mud volcanoes are a source of greenhouse gas emissions to the atmosphere. Gas–geochemical monitoring is conducted for the first time in the Gladkovsky and Oldenburgsky’s mud volcanoes. It is established that the flow rate of the mud volcanic gases is much more variable in comparison with their chemical composition. The chemical composition of mud volcanic gases in different salses of the same volcano is reliably distinct. The measured CH₄ flux from macroseeps (salses) is 0.5 ± 0.1 and 2.84 ± 0.32 t/year for the Gladkovsky and Oldenburgsky’s volcanoes, respectively. The theoretical estimation of the total CH₄ flux (from mini- and macroseeps) is ~5 and 6 t/year for the Gladkovsky and Oldenburgsky’s volcanoes, respectively. It is shown that the Bernard’s coefficient for mud volcanic gases is negatively correlated with their emission rate.</p>