Introduction: Due to the high radiation dose used in radiotherapy, the human tissue is usually replaced with tissue substitutes in order to develop new treatment techniques. Tissue substitutes have not been reported for colorectal cancer tissue (CRC). This study aims at developing tissue substitutes for the CRC tissue with respect to the mass attenuation (µ, m) and mass energy absorption coefficients (µ, en/ρ, ) within the energy range of 6 –,15MV. Material and Methods: Colorectal cancer tissue and four locally sourced materials namely beeswax, gelatine, rice powder, clay, and their mixtures –,Clarice, gelarice, gelaclay, and bewaclay were subjected to Rutherford Backscattering Spectrometry (RBS) to determine their elemental composition. Results from the RBS were used in XCOM, a web-based photon interaction software designed by the National Institute of Standards and Technology, USA to determine their theoretical µ, m and µ, en/ρ,values. Again, these materials were exposed to a narrow beam of x-rays at energies of 6 and 15MV to obtain their experimental µ, m and µ, en/ρ,values. Results: Revealed that the ratio of CRC tissue to the test materials ranged from 0. 946 (beeswax) to 1. 07 (clay) for both theoretical and experimental values with bewaclay having a ratio of 1. 01 compared with 1. 00 for CRC and a p = 0. 541 and p = 0. 663 with respect to µ, m and µ, en/ρ,respectively. Conclusion: Bewaclay with the closest match can be used as a tissue substitute for the CRC tissue between 6 –,9MV with respect to µ, m and µ, en/ρ,as parameters for matching.