New limits on double-beta decay of ^190 Pt and ^198 Pt

search for double-beta decay of ^190 Pt and ^198 Pt with emission of γ -ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of ^190 Pt relative to different channels and modes of the decays were set on the level of lim T_1/2∼ 10^14 – 10^16 year. A possible exact resonant 0ν KN transition to the 1,2 1326.9 keV level of ^190 Os is limited for the first time as T_1/2≥ 2.5 × 10^16 year. A new lower limit on the double-beta decay of ^198 Pt to the first excited level of ^198 Hg was set as T_1/2≥ 3.2× 10^19 year, one order of magnitude higher than the limit obtained in the previous experiment.