We report results of an investigation of Be diffusion from an In0.53Ga0.47As layer with Be doping level of 3 x 10(19) cm(-3), sandwiched between undoped InP layers. The InP/In0.53Ca0.47As/InP heterostructures, grown by gas source molecular beam epitaxy were subjected to 10-240s halogen lamp rapid thermal annealing of 700-900 degreesC. The observed Be depth profiles, obtained by the secondary ion mass spectrometry (SIMS) technique, could be explained by a kick-out diffusion involving neutral Be interstitial species in InGaAs and singly ionized Be interstitial species in InP,