The effect of Roxithromycin (RZ) on corrosion of aluminium in 0.1N Hydrochloric acid was investigated using weight loss measurements, potentiostatic polarization techniques and scanning electron microscopy The results showed that RZ is an effective inhibitor for aluminium in 0.1N HCl and inhibition efficiency is >90% at inhibitor concentration of 450ppm beyond this concentration its efficiency decreases. Polarization studies showed that RZ behaves as a mixed inhibitor. Electrochemical impedance studies were used to investigate mechanism of corrosion. Quantum chemical calculations were performed on roxithromycin and different quantum chemical properties were calculated and discussed. © 2014 University of Manchester and the authors.