This disclosure pertains to the use of black liquors from kraft pulp mills as a source of catalysts for the thermochemical conversion of organic matter feedstocks to bio oils. More particularly, some embodiments pertain to integrated kraft pulp mill and thermochemical conversion systems, which include: a Kraft pulp mill comprising a digester for digesting a lignocellulosic material with white liquor to produce pulp and black liquors; a thermochemical conversion subsystem comprising: at least one mixing tank for combining pulping liquors received from the pulp mill with an organic matter feedstock and water to produce a reaction mixture; a reactor vessel for treating the reaction mixture received from the mixing tank at a reaction temperature and pressure suitable for conversion of all or a portion of the organic matter in the reaction mixture into a product mixture comprising a bioproduct and an aqueous stream containing both organic and inorganic compounds; and a depressurizer for depressurizing product mixture received from the reactor vessel; and one or more conveyors for conveying the pulping liquors from the pulp mill to the mixing tank.