The study of then-tricosane (n-C23H48):n-pentacosane (n-C25H52) mixtures was carried out using X-ray analyses. In spite of what is found in the literature, the X-ray diffraction results show the presence of six orthorhombic solid solutions when the molar concentration inn-pentacosane increases: three terminal solid solutions, denoted β0(C23), β′0(C23) and β0(C25), isostructural withn-tricosane andn-pentacosane structures and three orthorhombic intermediate phases, denoted β″1, β′ and β″2. On the basis of powder X-ray patterns, the phases β″1and β″2are indistinguishable and they are isostructural with the solid solution β″ of the binary systemsn-C22H46:n-C24H50andn-C24H50:n-C26H54. The orthorhombic intermediate solid solution β′ is also isostructural with the phases β′1and β′2of the binary systemsn-C22H46:n-C24H50andn-C24H50:n-C26H54. The six solid solutions ranges are determined by the X-ray patterns examination of twenty seven mixtures at 20°C.