The dielectric properties of monoclinic manganese tungstate have been studied as a function of frequency and temperature. It was found that the dielectric constant and dielectric loss for all temperatures had high values at low frequencies which decreased rapidly as frequency increased attaining a constant value at higher frequencies. The a.c. conductivity increased as frequency increased, conforming small polaron hopping. As temperature increased, the values of the a.c. conductivity are shifted to higher values. Higher values were also obtained when the particle size decreased. These properties make the nano-sized MnWO4 as a promising material for fabricating humidity sensors.