This paper deals with the dynamic characteristics of hemispherical sandwich shells with electro-rheological (ER) fluid core under clamped free and clamped clamped conditions. The free vibration and damping analysis is carried out by using the semi-analytical finite element method. Three noded line elements with seven degree of freedom per node are used in meridional direction and Fourier series is assumed in circumferential direction. There are two types of electro-rheological fluid cores used in the present study. The damping variation of hemispherical sandwich shell for different radius to thickness (R/t) ratio and core to facing thickness ratio (tc/tf) are carried out. The variation of damping properties of ER fluid with electric field is also investigated.