The E-1 and E-1 + Delta(1) energy bands of metal-organic chemical vapor deposition grown AlxGa1-xAs, with x in the range 0-0.55, have been determined using photoreflectance technique. The aluminum composition for each sample was determined using the energy of the room-temperature photoluminescence compensated peak value and a suitable fundamental band gap formula. The positions of the E-1 and E-1 + Delta(1) peaks were determined from curve-fitting an appropriate theoretical model to our experimental data by a modified downhill simplex method. Using the results, we propose new E-1 and E-1 + Delta(1) cubic expressions as functions of the aluminum composition, x, and compare them with the available reported expressions. (C) 2003 Elsevier B.V. All rights reserved.