In enzymology, a L-xylose 1-dehydrogenase (EC 1.1.1.113) is an enzyme that catalyzes the chemical reaction

L-xylose + NADP⁺ ${\displaystyle \rightleftharpoons }$ L-xylono-1,4-lactone + NADPH + H⁺

Thus, the two substrates of this enzyme are L-xylose and NADP⁺, whereas its 3 products are L-xylono-1,4-lactone, NADPH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The systematic name of this enzyme class is L-xylose:NADP⁺ 1-oxidoreductase. Other names in common use include L-xylose dehydrogenase, and NADPH-xylose reductase.