Pure INCO, ISCN, and the hitherto unknown molecule ISeCN have been prepared in the HeI photoelectron spectrometer (PES) by the heterogeneous reactions of ICl gas with AgNCO, AgSCN at room temperature, and AgSeCN at -9 (+/- 1) degrees C, respectively. They were characterized on line by PES experiments and OVGF calculations. The well-matched results between the PES experiments and OVGF calculations not only show that the new reaction is a good reaction to prepare pure INCO and pure ISCN, but also that the new compound prepared by passing the ICl gas over the freshly AgSeCN powder at -9 (+/- 1) degrees C is the hitherto unknown ISeCN.