This Project is about the study of rst order necessary and su cient conditionsrnfor unconstrained cone d.c. programming problems where the underlinedrnspace is partially ordered with respect to a cone.These conditionsrnare given in terms of directional derivatives and sub di erentials of the componentrnfunctions.Moreover,conjugate duality for cone d.c.optimization is discussedrnand weak duality theorem is proved in a more general partially orderedrnlinear topological vector space.