Ignition criteria and fusion power density are calculated for catalysed-D and D-3He plasmas for hot-ion-mode (Ti > Te) operation facilitated by a large ratio of the ion energy confinement time to the electron energy confinement time. The optimistic case of complete transfer of the energy of the charged-particle fusion products to the ions is considered; this case further enhances hot-ion-mode operation. Even though hot-ion-mode operation increases the fusion power density, the maximum pressure-limited fusion power densities in catalysed-D and D-3He are at least a factor of thirty times lower than those in D-T plasmas; as a result the achievement of very high plasmas beta and/or the maximum use of high-field magnet technology are needed in order to attain high wall loadings and moderate thermal output power levels in D-D and D-3He reactors. The implications of ignition requirements on machine design are determined for tokamak plasmas; the electron energy confinement time is assumed to be given by an empirical energy scaling law, τe ∼ na2. The thermal stability of advanced fuel plasmas is studied. It is found that the runaway time is short compared to the energy confinement time for ion temperatures that maximize the fusion power of a pressure-limited plasma.