  When Higgs boson candidates will be found at future colliders, it becomes
imperative to determine their properties, beyond the mass, production cross
section and decay rates. Other crucial properties are those related to the
behaviour under CP transformations, and the self-couplings. This paper
addresses the question of measurability of some of the trilinear couplings of
MSSM neutral Higgs bosons at a high-energy e^+e^- collider, and the
possibilities of exploring the Higgs boson CP properties at e^+e^- and e^-e^-
colliders.
