ABSTRACT: WE PROPOSE SIMULTANEOUS 100 KS XMM-NEWTON AND NUSTAR OBSERVATION OF THE SEYFERT 1.5 GALAXY ESO 368-G18 FOR THE PURPOSE OF MAKING A DETAILED STUDY OF THE SPECTRUM OF RADIATION REFLECTED FROM THE INNER ACCRETION DISK. OUR CHIEF AIM IS TO CONSTRAIN BOTH THE SPIN OF THE BLACK HOLE AND THE PROPERTIES OF THE CORONA THAT ILLUMINATES THE DISK. THE COMBINATION ON NUSTAR S HIGH-SENSITIVITY IN THE HARD X-RAY BAND THE SOFT-BAND COVERAGE OF IT AND OUR STATE OF THE ART RELATIVISTIC REFLECTION MODELS WILL ALLOW US TO BREAK DEGENERACIES BETWEEN DIFFERENT POSSIBLE SCENARIOS AND IMPOSE TIGHT CONSTRAINTS ON THE ACCRETION GEOMETRY AND BLACK HOLE SPIN OF THIS BRIGHT AGN.