The enantioselective synthesis of two enantiomers of 3‐methylthiodecanal was described, in which the optically active 1‐undecen‐4‐ols prepared by asymmetric catalytic addition of n‐octanal with allyltributylstannane went through oxidation of double bond and nucleophilic substitution of hydroxy group via mesylate to afford the target molecules with about 90% ee values. Odour properties and approximate thresholds were determined by means of GC/Olfactory. The data indicated that two enantiomers of 3‐methylthiodecanal presented distinctive odour feature from each other and also a slight difference in odour intensity.