In enzymology, cis-dihydroethylcatechol dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are cis-1,2-dihydro-3-ethylcatechol and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are 3-ethylcatechol, reduced NADH, and a proton.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is cis-1,2-dihydro-3-ethylcatechol:NAD+ oxidoreductase. This enzyme participates in ethylbenzene degradation.