Lamellar phases composed of fluid dioleoylphosphatidylcholine (DOPC) bilayers containing alkan-1-ols (CnOH, n = 8, 10, 14, 16, 18 is the number of carbon atoms) at CnOH : DOPC = 0.3 molar ratio and hydrated with heavy water at 20.2 ≥ D2O : DOPC ≥ 14.4 molar ratio were studied by neutron diffraction. The bilayer thickness d(L) and the bilayer surface area A(L) per DOPC at the bilayer-water interface were obtained from the lamellar repeat period d using molecular volumes of DOPC, CnOH and D2O, and the Luzatti's method. Both the d(L) and A(L) increase with the CnOH chain length n at CnOH : DOPC = 0.3 molar ratio: d(L) = (3.888 ± 0.066) + (0.016 ± 0.005)·n (in nm), A(L) = (0.6711 ± 0.0107) + (0.0012 ± 0.0008)·n (in nm²).