EN
The electronic properties of Sr_{1-x}A_{x}CuO_{2+δ} (A = La, K, Ca) were examined. The crystal structure of the synthesized compounds was identified as orthorhombic with some admixture of tetragonal phase. For Sr_{1-x}La_{x}CuO_{2+δ} the insulator-metal like transition was observed with increasing La content. The d_{x²-y²} ground state of Cu ions was deduced from electron spin resonance measurements. The electronic state of Cu ions and their surrounding local symmetry was also found to be La and oxygen content dependent.