Method for producing a renewable base oil composition from a feedstock of biological origin, the method comprising: a) providing a feedstock, the feedstock comprising at least 5 wt% of a mixture of saturated free fatty acids and at most a remainder of one or more compounds selected from the list consisting of: unsaturated free fatty acids, fatty acid esters, fatty amides, fatty alcohols, as well as fatty acid glycerols such as mono-glycerides, di-glycerides and tri-glycerides of fatty acids; b) separating the feedstock into at least: - a saturated fatty acid enriched feed comprising at least 90 wt% saturated C n free fatty acids, where n is selected from one of the integer values 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; and no more than 3 wt% unsaturated free fatty acids; and - one or more saturated fatty acid depleted feed(s); c) subjecting the saturated fatty acid feed to ketonisation reaction conditions where two fatty acids react to yield a ketone stream, the ketone stream comprising as the major part saturated ketones having a carbon number of 2n-1 in the presence of a ketonisation catalyst; wherein the ketonisation reaction conditions comprise a temperature in the range from 300 to 400 °C, a pressure in the range from 5 to 30 barg, a WHSV in the range from 0.25 to 3 h -1, and a presence of a gas in the range from 0.1 to 1.5 gas/feed ratio (w/w), the gas being selected from one or more of: CO 2, H 2, N 2, CH 4, H 2 O; further wherein the ketonisation catalyst is TiO 2; and d) subjecting the ketone stream to both hydrodeoxygenation reaction conditions and to hydroisomerisation reaction conditions, simultaneously or in sequence, to yield a deoxygenated and isomerised base oil stream comprising the renewable base oil; e) optionally distilling the product of step d) to obtain a distilled renewable base oil; wherein no pre-treatment by hydrogenation or by hydrolysis is made in or in-between steps a) - c). a) providing a feedstock, the feedstock comprising at least 5 wt% of a mixture of saturated free fatty acids and at most a remainder of one or more compounds selected from the list consisting of: unsaturated free fatty acids, fatty acid esters, fatty amides, fatty alcohols, as well as fatty acid glycerols such as mono-glycerides, di-glycerides and tri-glycerides of fatty acids; b) separating the feedstock into at least: - a saturated fatty acid enriched feed comprising at least 90 wt% saturated C n free fatty acids, where n is selected from one of the integer values 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; and no more than 3 wt% unsaturated free fatty acids; and - one or more saturated fatty acid depleted feed(s); - a saturated fatty acid enriched feed comprising at least 90 wt% saturated C n free fatty acids, where n is selected from one of the integer values 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; and no more than 3 wt% unsaturated free fatty acids; and - one or more saturated fatty acid depleted feed(s); c) subjecting the saturated fatty acid feed to ketonisation reaction conditions where two fatty acids react to yield a ketone stream, the ketone stream comprising as the major part saturated ketones having a carbon number of 2n-1 in the presence of a ketonisation catalyst; wherein the ketonisation reaction conditions comprise a temperature in the range from 300 to 400 °C, a pressure in the range from 5 to 30 barg, a WHSV in the range from 0.25 to 3 h -1, and a presence of a gas in the range from 0.1 to 1.5 gas/feed ratio (w/w), the gas being selected from one or more of: CO 2, H 2, N 2, CH 4, H 2 O; further wherein the ketonisation catalyst is TiO 2; and d) subjecting the ketone stream to both hydrodeoxygenation reaction conditions and to hydroisomerisation reaction conditions, simultaneously or in sequence, to yield a deoxygenated and isomerised base oil stream comprising the renewable base oil; e) optionally distilling the product of step d) to obtain a distilled renewable base oil;