The effect of sapropel nature on the conversion of organic matter and composition of liquid products in catalytic hydroliquefaction was studied. It was shown that the maximum conversion is achieved for the samples in which the organic matter is represented mostly by protein residues. For phytogenic sapropels the conversion is much lower. Investigation of the composition of liquid products revealed that an increase in the fraction of protein component in liquid products of hydroliquefaction leads to a decrease in the amount of oxygen-containing compounds and an increase in the fraction of nitrogen-containing compounds and hydrocarbons.