Dielectric properties of pure, unsintered and pressed barium ~tanate were investigated: The .initial nonlinear variation of dielectric constant and dissipation factor with temperature observed s attrIbut.ed to the water vapor adsorbed on the surface exposed to the pores. The absence of ferroe.lectnc propertIes and the linearity in dielectric constant and dissipation factor with temperature found III a heat-t~eated sample are explained on the basis of a nonferroelectric ~urface l~yer .. This was supported by the experIment showing the decrease in dielectric constant with decreasmg partIcle size.