Matrix certified reference materials (CRMs) are versatile tools to support quality, correctness and credibility of measurement results. CRMs are used to provide the traceability of the measurement results to the SI unit. Seven low alloy steel certified reference materials were developed by the national institute of standards (NIS), Egypt.  Homogeneity is studied using x-ray fluorescence spectrometer (XRF) and optical emission spectrometer (OES). The characterization of RMs was performed using independent chemical methods as gravimetric methods, x-ray fluorescence spectrometry, optical emission spectrometry and atomic absorption spectrometry.  Both the assigned values and their associated uncertainty were calculated by weighted mean approach after the statistical analysis of the results of measurements for the homogeneity of variances, equality of means, normality of data and outliers.