Process for the preparation of a linear aldehyde organic compound by hydroformylation (b) starting from an internally unsaturated functionalised organic compound whereby first (a) a portion of the internally unsaturated functionalized organic compound is isomerized to a terminally unsaturated functionalised organic compound in the presence of a suitable isomerization catalyst, wherein following the isomerization step (a), the hydroformylation (b) is effected in the presence of carbon monoxide, hydrogen and a catalyst which preferentially catalyzes the hydroformylation reaction of the terminally unsaturated functionalised organic compound to the linear aldehyde organic compound, the internally unsaturated functionalised organic compound remaining practically unhydroformylated, whereupon (c) the linear aldhyde organic compound is separated out of the mixture and (d) the remainder of the unsaturated functionalised organic compound-containing mixture is recirculated to the isomerization step (a).