A computational analysis was made for the large number of available critical experiments with hydrogenous mixtures. The calculations were made using both multigroup S4 and diffusion theory with 18 energy groups obtained with the GAMTEC-II code. Resonance capture by the isotope 240Pu was treated in the NR and NRIA approximations. Rather good agreement was found between experiment and theory. The results are given as a parametric survey for Pu densities ranging from 0.015 to 1.0 g/cm3. The calculated minimum critical mass of 239Pu is 547 g for water-reflected aqueous Pu(NO3)4 solutions and 531 g for similar mixtures of 239Pu and water.