I guess that a fuel-cell hybrid may have a hydrogen ICE that works much like the prius or HCH whereas it adds power when needed and/or charges the batteries and only requires H2 as a fuel for both the ICE and fuel-cell (zero emissions)??? Or the ICE may just run on gasoline/diesel as back-up for the fuel cell part of the drive train that uses H2.

more info from toyota site..

FCHV-5 is a fuel-cell hybrid vehicle that generates electricity from hydrogen derived from CHF (Clean Hydrogen Fuel), using Toyota's original CHF reformer. Seen as the next generation liquid fuel, CHF can be produced from crude oil, natural gas or coal and it has a low sulfur content. CHF is also used as a fuel for gasoline engine vehicles and can be supplied by current gasoline pumps. Therefore, FCHV-5 will be useful where hydrogen supply infrastructure is not available.

While the FCHV-5 shares several main fuel-cell components with the FCHV-4, such as its fuel-cell stack and motor, its CHF reformer packaged with a newly developed catalyst and heat exchanger, among other components, offers excellent acceleration and high fuel efficiency. Toyota continues to strive to optimize the layout of the FCHV-5's fuel-cell related components and has already been able to locate all such components beneath the floor of the vehicle, so as to not compromise interior cabin space. Along with additional efforts to make the system more compact, we are also endeavoring to cut down on the system's start-up time.