Group V element exchange during the growth of GaAs/Ga0.51In0.49P quantum wells (QWs) by chemical beam epitaxy is investigated by photoluminescence (PL) experiments as a function of temperature from 4 to 300 Ii. In order to study the As-P exchange at the direct interface of the GaAs QW, the GaInP2 surface is exposed to a cracked AsH3 how during various times. The QW free exciton energy is deduced at 4 Ii by fitting the temperature dependence of the PL energy with the classical expression E(T) = E-0 - a[1 + 2/{exp(theta/T) - 1}]. The calculation of the E1HH1 energies are carried out by taking into account the following phenomena which affect the QW structure : indium segregation, As-P exchange and As and P residual incorporations. It is found that As-P exchange rate decreases with the increase of the cracked AsH3 exposure time.