Layered 3d metal ABO2 oxides have recently attracted a lot of interest due to their variety of properties. Continued efforts are made to study such transition metal oxides ABO2 especially for oxygen insertion, essential in many applications, such as energy conversion, oxygen sensing or oxygen storage. Among these multi functional materials, the crednerite Cu1+xMn1-xO2 solid solution presents rich physics and promising applications. Considering its complexity, the aim of this project is to give more information about the impurity effects (oxygen excess/nonstoichiometry, substitution with nonmagnetic elements) upon the relationship structures/properties in these materials. Our study will be a step forward in understanding the stability of these materials and even a possibility of tuning their properties.