PURPOSE: To enable the combined production of the titled compounds under mild condition, by using 2-hydroxy-4-methyltetrahydropyran as a raw material, and reacting in a non-oxidizing gas atmosphere under specific temperature and pressure condition in the presence of the oxide of a metal selected from copper, chromium and zinc.

CONSTITUTION: β-Methyl-δ-valerolactone and 3-methylpentane-1,5-diol are produced at the same time (preferably at amolar ratio of 9/1W1/9) by reacting 2-hydroxy-4-methyltetrahydropyran in a non-oxidizing gas atmosphere (preferably nitrogen gas or hydrogen gas) at 110W190°C, especially 130W180°C under a pressure of ≤50 abs.atm, especially 0.01W20 abs.atm, in the presence of the oxide of one or more kinds of metals selected from copper, chromium and zinc.

USE: A raw material of polyurethane, piant-modifier, resin modifier, etc., and intermediate for pharmaceuticals, agricultural chemicals, perfumes, etc.