The low temperature optical absorption spectra of fully coherent strain-compensated InAsxP1-x/GayIn1-yP (0.15≤x≤0.27; 0.09≤y≤0.13) multilayers grown on InP(001) by organometallic vapor phase epitaxy were measured using a Fourier transform infrared interferometer. All spectra show well-resolved excitonic transitions. The analysis with a solution to the Schrödinger equation in the envelope function formalism using the Bastard–Marzin model allows to determine accurately that the strained conduction band offset δEc equals (776±4)x meV, or 77%±2% of the total strained band gap difference. The heterojunction alignment is of type I for both heavy- and light-hole bands but the light-hole confinement is very shallow. The heavy- and light-hole exciton binding energies obtained from the analysis are ≃9 and 6–7 meV, respectively. © 2000 American Institute of Physics.