In addition to the 411.77 kev. γ-ray transition, two γ-ray transitions of energies 676.5 ± 0.8 kev. and 1088.9 ± 0.9 kev. have been observed in Hg198 following the disintegration of Au198. The intensities of these transitions were found to be (8.20 ± 0.56) × 10−3 and (1.63 ± 0.12) × 10−3 per disintegration respectively. The K conversion coefficient of the 676.5 kev. transition was measured as 0.0224 ± 0.0019, identifying the radiation as a mixture of magnetic dipole and electric quadrupole. The K conversion coefficient of the 1088.9 kev. transition was measured as 0.00450 ± 0.00034, identifying this radiation as electric quadrupole.A β-transition to the ground state of Hg198, of energy 1371 kev. and intensity (2.5 ± 0.5) × 10−4 per disintegration, has been observed and identified as a third order forbidden, transition. The shape of this spectrum has been studied above the end point of the intense 959 kev. β-transition. Of the four combinations considered for the β-decay interaction form, viz. SA, VA, ST, VT, it was found that the experimental shape can be fitted by any one of VA, ST, or VT, but not by SA. The log f0 t value for the transition is 11.7.A disintegration scheme is proposed in which the excited states of Hg198 at 412 and 1089 kev. are each assigned spin 2 and even parity and the ground state of Au198 spin 3 and odd parity.