This letter presents a simple, quick, nondestructive method for the determination of ordering in Ga0.51In0.49P layers using x‐ray diffractometry. The skew, symmetric arrangement of x‐ray reflection was used for this purpose enabling the measurements of all allowed (hkl) reflections. Ordered Ga0.51In0.49P layers grown by metalorganic vapor‐phase epitaxy at different substrate temperatures were studied. The {1/2,1/2,1/2}, {1/2,1/2,3/2}, and {1/2,1/2,5/2} reflections of the ordering‐induced monolayer superlattices have been observed. The experimental results are discussed in detail, demonstrating that x‐ray diffractometry is a powerful means to evaluate ordering in semiconductors. ©1995 American Institute of Physics.