  We present long-slit HST/STIS measurements of the ionized-gas kinematics in
the nucleus of three disk galaxies, namely NGC 2179, NGC 4343, NGC 4435. The
sample galaxies have been selected on the basis of their ground-based
spectroscopy, for displaying a strong central velocity gradient for the ionized
gas, which is consistent with the presence of a circum nuclear keplerian disk
(CNKD, Bertola et al. 1998; Funes et al. 2002) rotating around a super massive
black hole (SMBH). For each target galaxy we obtained the H_alpha and [NII]
6583 AA kinematics along the major axis and two 0"25 parallel offset positions.
Out of three objects only NGC 4435 turned out to have a disk of ionized gas in
regular motion and a regular dust-lane morphology. Preliminary modeling
indicates a SMBH mass one order of magnitude lower than the one expected from
the M-sigma relation for galaxies (Ferrarese & Merritt 2000; Gebhardt et al.
2000).
