Calculations of the reflectance for antireflection coating (ARC) made of porous silicon (PSi) were carried out. Although PSi has been the focus of interest in the last few years, a satisfactory model for calculation of its reflectance features is still absent. A combination of the optical matrix method and a graded-band gap model of PSi. which takes into account the gradient in porosity, has recently been suggested. Calculations based on the optical matrix method were carried out also for well-known ARC like MgF2, ZnS and Ta2O5 in order to prove the feasibility of the method. Good agreement with experimental data was found for all ARC types.