The paper presents the results of substantiation of the possibility of using mechanochemical activation of hydrolytic lignin, including mechanical processing in a high-speed mill with the addition of soda ash, for its further use as a component of fuel briquettes in combination with birch sawdust. The water extract of lignin without treatment and after activation in the mill was evaluated to substantiate the necessity of using soda ash to neutralise its acidic component so that the pH level of the water extract of lignin without treatment is 3.70. It was obtained that the addition of soda ash in the amount of 500 g/t allows increasing the pH level of aqueous extract of lignin after treatment from 3.70 to 7.03. It was found that the application of thermal treatment of birch sawdust with the addition of soda ash and subsequent activation in a high-speed mill leads to an increase in the value of activation energy of samples, which is confirmed by thermal analysis methods when analysing data obtained at three heating rates. The average value of activation energy for lignin after mechanochemical activation is 188.63 kJ/mol, for birch sawdust 311.03 kJ/mol. The possibility of application of mechanochemical activation for hydrolytic lignin and birch sawdust has been substantiated, consisting in the synergetic effect of mechanical activation by grinding in a planetary mill and chemical activation, which will allow to obtain high-quality briquettes with high calorific value.