Radial distributions of He +, He + 2 and Kr + were measured in a hollow cathode discharge in He and in He-Kr mixtures using a mass spectrometer. The dimensions of the discharge were similar to those used in He-Kr + hollow cathode discharge lasers. From the ion densities the electron density was derived. Introducing krypton into the helium discharge results in decreasing both the densities of He + and He + 2 ions. During this process the radial distributions of the He +, H + 2 and electron density change from parabolic into saddle-like profiles. The changes of radial profiles of the charged particles in the He-Kr hollow cathode discharge may affect the lasing properties of the mixture.