The paper presents the results of vacuum-free electric arc synthesis of catalysts based on molybdenum carbides, which can be used for hydrogen production by electrochemical water splitting. The synthesis of carbide phases is possible due to self-shielding effect of the reaction volume during DC arcing in open-air environment. According to X-ray diffractometry data, there are two phases of molybdenum carbides in the synthesized product: Mo2C and Mo1.2C0.8, the phase of initial molybdenum, and the phase of graphite were identified. In a series of experiments, the authors were able to control the phase composition of the synthesis product by changing the distance between the initial reagents and the zone of initiation and combustion of the arc discharge. The estimated catalytic activity of the synthesized samples is close to the activity of catalysts based on molybdenum carbides obtained by other methods.