The crystal structure of 5,10,15,20-tetra(ethoxycarbonyl)porphyrin copper(II) showed that its central copper has a six-coordinate structure. An efficient copper porphyrin-catalyzed cross-dehydrogenative coupling (CDC) esterification reaction between C(sp³)–H and carboxylic acids using di-tert-butyl peroxide (DTBP) as an oxidant was established. The kinetic isotope effect (KIE) indicated that C(sp³)–H bond cleavage was the rate-determining step of this CDC reaction.