A process for the preparation of 2-methyl-2-sec.butyl-1,3-propanediol comprising hydroformylating 2-methyl-1-butene with carbon monoxide and hydrogen in the presence of a first catalyst to form the substance 3-methyl-pentanal, condensing said substance with formaldehyde, or a compound which forms formaldehyde under the conditions of condensation in a basic medium to form alpha-sec.butyl-acrolein, partially hydrogenating said acrolein in the presence of a second catalyst to form the material 2,3-dimethyl pentanal, and converting said material into said diol by treatment with formaldehyde, or a compound which forms formaldehyde under the conditions of conversion, in the presence of a strong base as a third catalyst.The compound of the present invention is useful as an intermediate in the production of pharmaceuticals and drugs; in particular, the production of carbamates which are useful as tranquilizers and blood pressure lowering agents.