  We study the morphology and kinematics of the ionization state of the gas in
four 'green valley' early-type galaxies at different stages of their transition
from a 'blue cloud' of star-forming galaxies to the sequence of passive
evolution. The previous HI mapping of the considered sample reveals a spatial
offset between the cold gas reservoirs and stellar discs depending on the
post-starburst age. Consideration of the ionized-gas properties is essential to
understand the role of various feedback processes in star formation quenching.
We performed long-slit and 3D optical spectroscopic observations at the 6-m
Russian telescope and compared the gas and stellar kinematics. Spatial
distribution of the ionized gas is in agreement with HI maps; however, the
one-order higher angular resolution in the HII velocity fields allows us to
study non-circular gas motions in detail, like the AGN-driven outflow in the
nucleus of J1117+51. The most intriguing result is the global HI+HII gas
counter-rotation relative to the stellar disc in J1237+39. Therefore, in this
case all the observed gas in the 'green valley' galaxy was captured from the
environment via accretion or minor merging.
