Highly ordered nanoporous anodic alumina (NAA) membranes with varying pore properties were fabricated using two step electrochemical oxidation of aluminum. A study on optical reflective interferometric properties of NAA was conducted. The influence of pore properties including pore diameters, interpore distance and pore lengths on the reflection spectra was explored. Variation of reflection intensities with different angles of incidence showed the iridescence of NAA membranes. Such NAA nanostructures are promising for the use as substrates for various biomedical sensing applications.