Abstract Climate change caused by fossil fuels has driven the search for bioenergy sources. Elephantgrass [ Cenchrus purpureus (Schumach.) Morrone] biomass is a promising alternative for diversifying the energy matrix. One of the main steps of a genetic breeding program is the selection of parents who will form the crossing block, and the use of diallel analysis is critical in this step. Therefore, this study aimed to use mixed linear models to analyze diallel crosses and estimate the general combining ability (GCA) and specific combining ability (SCA) of elephantgrass clones to select superior parents and hybrids for bioenergetic applications. Eleven parents were crossed in a diallel scheme, totaling 55 hybrid combinations, and evaluated in a randomized complete block design with three replications. The measured traits were dry biomass production (DBP), in vitro dry matter digestibility (IVDMD), and cellulose‐lignin (C:L) ratio. There was a significant effect of SCA, SCA × cut interaction, and permanent effect on DBP, and a significant effect of GCA on IVDMD and C:L. There was a predominance of genes with additive effects controlling IVDMD and C:L traits, and dominance and epistasis for DBP. The parents selected for biochemical conversion processes were Embrapa's Active Germplasm Bank of Elephantgrass (BAGCE) 38 and CNPGL 92‐38‐2. The parents selected for direct combustion of biomass were BRS Canará, BRS Capiaçu, and CNPGL 96‐27‐3. The hybrids BAGCE 21 × BAGCE 38, BAGCE 30 × CNPGL‐92‐38‐2, and BAGCE 38 × BRS Kurumi show potential for the production of dry biomass.