  Spectroscopic and imaging data of the peculiar galaxy Mkn 298 are presented
in this paper. Narrow-band Halpha and broad-band R images are used to study the
star formation rate in the galaxy and its morphology, which is typical of a
merging system. Long-slit and integral field spectra are used to assess the
kinematics of gas and stars, and the nature of the ionizing source at different
distances from the nucleus. In particular, the nucleus of Mkn 298 is
characterized by peculiar line ratios: [NII] 6583/Halpha is typical of HII-like
regions, while [OI] 6300/Halpha could indicate the presence of an active
galactic nucleus. We show that models where a shock component is added to
photoionization from a starburst allow to reproduce the observed line ratios.
Mkn 298 is thus most likely a star forming galaxy, rather than a galaxy hosting
an active nucleus.
