PURPOSE: To obtain novel odorant substances dihydrocampholenic aldehyde deriv. having fruit-like, flower-like or woody accompanying odor and especially suitable for modification and reinforcement of known compositions.

CONSTITUTION: This substance is a compd. of formula I (wherein R is a group of formula II or formula III (R1-R3 are each H or a C1-4 alkyl; one of dotted lines represent an additional bond; R3 is present only when β or γ-unsatd.)), e.g. 3,3-dimethyl-5-(2,2,3-torimethyl-cyclopent-1-yl)-pent-4-ene-2-ol. The compd. of the formula I, wherein R is a group of formula II is obtained by subjecting a dihydrocampolenic aldehyde to Aldol condensation with a compd. of formula V.