Nuclear spins I, magnetic-dipole μ and electro-quadropole Q moments, and optical spectroscopic isotope and isomer shifts (I.S.) have been obtained for the neutron-deficient mercury isotopes and isomers with mass numbers from 192 to 195. The isotopes were produced by p, yn reactions on Au 197. Approximately 0.01μg of Hg was transferred into the rf-excited electrodeless light sources. A well-blazed plane diffraction grating, 25 cm wide, was used in the multiple wavelength monochromator of 11 m focal length for these high-resolution optical hfs measurements. These lead to the results I = 1 2 for Hg 195, I = 13 2 for Hg 195m and Hg 193m; μ = −1.05, 0.53, −1.04 nm for Hg 193m, Hg 195, Hg 195m; Q = 1.37, 1.41 b for Hg 193m, Hg 195m; with respect to Hg 198, I.S. = 0.441±0.020, 0.368 ±0.006, 0.284±0.007, 0.214±0.008, 0.220±0.005 cm−1 for Hg 192, Hg 193m, Hg 194, Hg 195 and Hg 195m. For Hg 193 the tentative results are I = 1 2 , μ = 0.56 nm, and I.S. = 0.350±0.027 cm −1; the last result was obtained by Walter and Stroke in a magnetic-scanning experiment. The isotope- and isomer-shift results, which have led to a hypothesis of the cause of odd-even staggering in isotope shift, are discussed qualitatively in the light of the polarizability of nuclei by nucleons (coupling of core-excited states with odd particle).