Unsupported and high specific surface area (S-BET) catalyst precursors for deep-hydrodesulfurization (deep-HDS) are obtained using an environmental friendly, continuous and fast synthesis process in supercritical water/alcohol mixtures. This approach offers an access to high production rate and upscaling. Two mixed oxides were synthesized: NiMoO4, which is the preferred material when deep-HDS is investigated, and CoMoO4 preferred for simple HDS. The role of the water/alcohol mixture on the resulting specific surface area has been studied and allows a controlled adjustment of the resulting specific surface area. The obtained NiMoO4 material consists of the highly active hydrate NiMoO4 center dot 0.75H(2)O phase with a controlled composition and specific surface area up to 200 m(2) g(-1). Resulting materials have shown great performances when tested in deep-HDS catalytic tests. (C) 2016 Elsevier B.V. All rights reserved.