The　characterization　of　reactive　solid-liquid　interfacial　energies　and　solid　surface　energies　is　a　pressing　problem　in　materials　science　and　surface　science.　Based　on　the　concept　that　unbalanced　forces　doing　work,　a　mathematical　formulation　between　surface　energies　and　interfacial　energies　for　reactive　wetting　is　presented.　The　resulting　formalism　has　significant　generality　in　which　the　equilibrium　Young＇s　equation　for　solid-liquid　interfacial　energies　is　just　a　special　case.　It　is　shown　that　a　solid-liquid　interfacial　energy　at　non-equilibrium　is　always　higher　than　that　at　equilibrium,　and　that　the　transformation　of　reactive　interfaces　to　equilibrium　interfaces　is　an　inevitable,　spontaneous　process.　The　numerical　range　of　solid-liquid　interfacial　energies　γsl　for　a　limited,　solid-liquid　interfacial　wetting　system　was　calculated　to　be　0　≤　γsl　≤　γsg.　The　calculation　methods　for　reactive　solid-liquid　interfacial　energies　and　solid　surface　energies　are　presented.　They　are　significant　for　composite　materials　and　weld,　powder　sinter,　package　of　electronic　devices,　and　other　surface　and　interfacial　issues　in　metallurgy.　©　2012　The　Author(s).