The elemental composition of electro-deposited black Cr solar selective coatings before and after heating in air by using secondary ion mass spectrometry (SIMS) was investigated for optical property analysis. In addition, black Cr selective coating exposed by solar radiation for 5 months was compared with heated sample. SIMS investigation shows that $OH^+$ bearing ions were related to a near surface region of CrOH and CrO compound. The optical degradation of this coating after heating at $500^{circ}C$ reveals that diffusion of the Cu and Ni elements in substrate material, the chemical interactions adjacent to the interface, and the interface width broadening.