A new inorganic material was used to produce hydrogen in situ by contact with water for reduction of unsaturated hydrocarbons. Phenylacetylene reduction into styrene and ethylbenzene was chosen as a model reduction reaction. We show that a fine control over the reaction yield and selectivity can be obtained by controlling the hydrogen release and such parameters of the synthesis as the temperature, water content and the speed of stirring. We found that the largest amount of water at 80 A degrees C and vigorous stirring result in the highest yield and selectivity of the reaction. An alternative way of reaction control is suggested as compared to a conventional way of a catalyst inhibition. The new possibility of the reaction control may be of a wide interest for the laboratory synthesis for a good number of hydrogenation reactions.