The Ni/Co-natural clay catalysts have been prepared for the conversion of algae oil into diesel-grade hydrocarbons. Methyl oleate was used as a model compound for the present study. Ni/clay catalyst promotes decarboxylation/decarbonylation, whereas remarkable selectivity in hydrodeoxygenation (HDO) is achieved with Co/clay catalysts. Powder XRD and DRS studies of substrate mixed catalysts reveal a more prominent adsorption of substrate molecules over the Ni surface, which results in low HDO selectivity of nickel catalysts by surpassing the essential contribution of acidic sites. The HDO process provides higher carbon atom economy and energy value over decarboxylation/decarbonylation, while further reducing the formation of greenhouse gases such as CO2 and CH4. Total yield of saturated hydrocarbons from algae oil was 84-86 wt % with similar selectivity. The HDO rates of different fatty acids present in algae oil were independent of the fatty acid chain length. The catalysts are cost-effective and recyclable, and metal leaching during hydroprocessing is less than 1 ppm in all cases. This process is advantageous in terms of metal-to-substrate ratio, use of solvents and their concentration, and comparable HDO selectivity over the previously reported catalysts. A hydroprocessing reaction was also performed under solvent free conditions, which could be useful in industrial applications of this approach. © 2017 American Chemical Society.