In this paper there were presented the results of studying accumulation and depletion in an inter-membrane compartment (m) of double-membrane osmotic-diffusive cell. This cell was contained two (Ml and M(r)), microporous and symmetrical flat polymeric membranes (Nephrophane and Cellulose IMP-1), separating three compartments (l, m, r) containing the heterogeneous binary and ternary nonelectrolytic solutions. The inter-membrane compartment (m) consists of the infinitesimal layer of solution. The volumes of compartment m and external compartment (l and r) fulfill the conditions Vm-->0 and Vl = Vr-->infinity respectively. As binary solutions were used the aqueous glucose, and as ternary--the glucose solutions in 0.75 mole.l-1 aqueous ethanol solution. In this system the solution concentrations fulfill the condition Cls > Co(ms) > Crs. In the initial moment Co(ms) = 0.5 (Cls + Crs). The calculations of a concentration in a steady-state Ci(ms) for configurations A and B of double-membrane osmotic-diffusive cell were elaborated. In configuration A solution with concentration Cls was placed in compartment above membrane Ml and water below membrane M(r). In configuration B--the sequence of solution was reversed. In case of the accumulation of substance in compartment m Ci(ms) > Co(ms), and a case of depletion--Ci(ms) < Co(ms).