Measurements are presented of Balmer alpha line profiles from plasma ions which have been neutralized by charge exchange with injected neutral hydrogen beams in the DITE tokamak. Doppler broadening of the Hα line is interpreted in terms of the ion temperature and line profiles are compared with neutral particle energy spectra in the regime where the plasma is transparent to the transport of neutrals from the core to the boundary. An asymmetry in the charge-exchange line profile is interpreted in terms of plasma rotation during neutral beam injection. The advantage of this method over conventional neutral analysis is seen in the context of the diagnosis of large, hot and dense tokamak plasmas.