This study explores atomic and molecular adsorption on a number of early transition-metalcarbides (TMCs) in NaCl structure by means of density-functional theory calculations. Theinvestigated substrates are the TM-terminated TMC(111) surfaces, of interest because ofthe presence of different types of surface resonances (SRs) on them and because of theirtechnological importance in growth processes. Also, TM compounds have shown potentialin catalysis applications. Trend studies are conducted with respect to both period andgroup in the periodic table, choosing the substrates ScC, TiC, VC, ZrC, NbC,δ-MoC, TaC, and WC (in NaCl structure) and the adsorbates H, B, C, N, O, F, NH,NH2, andNH3. Trends in adsorption strength are explained in terms of surface electronic factors, bycorrelating the calculated adsorption-energy values with the calculated surface electronicstructures. The results are rationalized by use of a concerted-coupling model (CCM), whichhas previously been applied successfully to the description of adsorption on TiC(111) andTiN(111) surfaces (Ruberto et al 2007 Solid State Commun. 141 48). First, the cleanTMC(111) surfaces are characterized by calculating surface energies, surface relaxations,Bader charges, and surface-localized densities of states (DOSs). Detailed comparisonsbetween surface and bulk DOSs reveal the existence of transition-metal localized SRs(TMSRs) in the pseudogap and of several C-localized SRs (CSRs) in the upper valenceband on all considered TMC(111) surfaces. The spatial extent and the dangling bondnature of these SRs are supported by real-space analyses of the calculated Kohn–Shamwavefunctions. Then, atomic and molecular adsorption energies, geometries, andcharge transfers are presented. An analysis of the adsorbate-induced changes insurface DOSs reveals a presence of both adsorbate–TMSR and adsorbate–CSRsinteractions, of varying strengths depending on the surface and the adsorbate. Thesevariations are correlated to the variations in adsorption energies. The resultsare used to generalize the content and applications of the previously proposedCCM to this larger class of substrates and adsorbates. Implications for otherclasses of materials, for catalysis, and for other surface processes are discussed.