We present Beppo SAX and XMM- Newton observations of MKN 231 .
These observations and in particular the BeppoSAX PDS data allowed us to unveil , for the first time , the highly absorbed ( N _ { H } \sim 2 \times 10 ^ { 24 } cm ^ { -2 } ) AGN component .
We find that : a ) the AGN powering MKN231 has an intrinsic 2-10 keV luminosity of 1 ^ { +1 } _ { -0.5 } \times 10 ^ { 44 } erg/s ; b ) the strong starburst activity contributes significantly in the 0.1-10 keV energy range .
We propose that the starburst activity strongly contributes to the far infrared luminosity of MKN 231 ; this is also suggested by the multiwavelength properties of MKN 231 .