  We applay the genus statistics to simulated CMB polarization maps,
constructed from the secondary-ionization cosmological models in experimental
situations comparable to those of forthcoming space experiments. We find that
both the cosmic baryon density and the spectral index of density perturbations
are strongly anicorrelated to the reionization redshift. Using the Fisher
matrix approach we show that the accuracy on the spectral index and optical
depth to the last scattering are improved in the case of genus statistics when
comparing with the accuracy obtained from the standard power spectrum
statistics.
