The concentration dependence of IR spectra of phenol and diphenols in the Ar matrix at T = 12 K is studied. The influence of sample annealing at 25-30 K on band intensities of isolated molecules and H-bonded homoassociates is considered. The effect of diffusion on the process of complex formation is estimated, and a simple quantitative model is developed, permitting one lo evaluate a fraction of the H-bonded complexes of different conpositions in the sample with different concentrations of the molecules of sufficiently high orientational mobility in the matrix. The dimers are shown to predominate among the H-bonded complexes of these molecules at a matrix dilution down to 1:100 due to the strong dependence of the orientational mobility of the complexes on their sizes. Integral extinctions of the valence vibration bands of free and H-bonded OH groups of phenols in the Ar matrix are calculated.