The evolution of the ionization potential of H2S doped in argon for argon densities between the dilute gas and the triple point liquid was obtained by means of field ionization. The field ionization spectra of H2S in argon were simulated by convoluting the spectrum obtained in pure H2S with the calculated polarization energy distribution between the H2S ion and the medium. The density dependence of the conduction band energy minimum V-0(rho) (relative to vacuum) was obtained from the energy difference between the experimental spectra and the simulations. Excellent agreement was found between these values and those obtained using a larger molecule, CH3I. The values of V-0(rho) are compared to recent theoretical calculations.