The system of Ca-Sr-Cu-O have been investigated. Two new compounds with compositions Sr~3Cu~5O~8~+~x and CuSrCu~3O~5~+~x have been discovered. Both are orthorhombic with a=3.950, b=11.479, c=13.420︿ for CaSrCu~3O~5~+~x and a=6.489, b=11.280, c=12.240︿ for Sr~3Cu~5O~8~+~x. The X-ray powder data for CaSrCu~3O~5~+~x, Sr~3Cu~5O~8~+~x, Sr~2CuO~3 and SrCuO~2 are presented. The oxidation state of Cu ion and oxygen contents are analyzied by iodometric titration. Sr~0~.~5Ca~0~.~5CuO~2 that has a similar structure with SrCuO~2 has been found and its X-ray data are presented also.

Key words: COMPOSITION, RHOMBIC SYSTEM, STRUCTURE, CALCIUM, COPPER, STRONTIUM