This paper presents the results of a pollution flashover study of station post insulators energized with DC voltage using a theoretical model. It has been observed from field experience and laboratory experiments that the shape and core diameter of the station post insulators have strong influence on the flashover voltage magnitude and hence on the specific leakage length required per unit flashover voltage, the mm/kV. It is of practical interest to study this phenomenon and characterize various types of insulators for their performance. A number of station post profiles with varying pitch and projection have been considered for this purpose. The effect of core diameter has also been studied. Results in line with the experimental findings of earlier researchers have been obtained. It is expected that the model can be used as an aid in the HVDC station design.