The reaction of joint obtaining of 2-methylcyclopentanone and methylcyclopentadiene with conjugated double bonds on the basis of products of liquid-phase oxidation of 1-methylcyclopentene over active Al₂O₃ of Al γ-mark promoted by hydroxide of potassium (2 mas. % KOH on Al₂O₃) was studied. The optimum conditions of reaction were revealed and it was established that at temperature 340⁰C received oxides under liquid-phase oxidation of 1-methylcyclopentene in the presence of tested catalyst (2 mas. % KOH on Al₂O₃) with 100% conversion and volume velocity of delivery 0.5–0.6 h^-1 are transforming to 2-methylcyclopentanone and methylcyclopentadienes-1,3. Their quantity under noticed con­ditions in obtained catalysate is 30–33 and 60–62 mas. % accordingly