Compositionally graded InxGa1-xP (from x = 0.48-1) layers have been grown on GaAs substrates with solid-source molecular beam epitaxy. Atomic force microscopy, high-resolution X-ray diffraction and photoluminescence (PL) were used to characterize a series of samples grown with different grading rates. It is found that all the samples are nearly fully strain relaxed and the value of the strain relaxation ratio is the same, which is consistent with the calculation from the theoretical model. The grading rate within the range of 1.09-2.53%/mum does not seem to influence the surface roughness, strain relaxation ratio, mosaicity and the PL spectra significantly. The results reported here will benefit the design of InGaP graded layer for practical use in metamorphic devices. (C) 2002 Elsevier Science B.V. All rights reserved.