THE X-RAY SPECTRAL ANALYSIS OF COMPTON THICK (CT- I.E. HAVING INTRINSIC OBSCURATION NH>1E24 CM^-2) ACTIVE GALACTIC NUCLEI (AGN) IS KEY TO UNDERSTAND THE PHYSICS OF THE OBSCURING MATERIAL SURROUNDING ACCRETING SUPERMASSIVE BLACK HOLES. WE PROPOSE TO TARGET WITH A COMBINED NUSTAR/XMM-NEWTON OBSERVATION THREE CANDIDATE CT-AGN SELECTED FROM THE BAT 100-MONTH SURVEY. THANKS TO THE EXCELLENT COUNT STATISTICS WE WILL BE ABLE TO ASSESS IF THESE SOURCES ARE IN FACT CT-AGN. WE WILL ALSO CONSTRAIN SEVERAL SPECTRAL PARAMETERS (E.G. RELATIVE IMPORTANCE OF THE SCATTERED COMPONENT VERSUS THE DIRECT ONE GEOMETRY OF THE OBSCURING TORUS EQUIVALENT WIDTH OF THE IRON EMISSION LINE). THIS ANALYSIS WILL REFINE OUR KNOWLEDGE ON THE TRUE INTRINSIC FRACTION OF CT-AGN AND THEIR CONTRIBUTION TO THE CXB.