Stepwise cyanation of tetrabromonaphthalenediimide (NDI) 1 gave a series of cyanated NDIs 2-5 with the monocyanated NDI 2 and dicyanated NDI 3 isolated. The tri- and tetracyano- NDIs 4 and 5 show intrinsic instability toward moisture because of their extremely low-lying LUMO energy levels. The partially cyanated intermediates can be utilized as air-stable n-type semiconductors with OFET electron mobility up to 0.05 cm(2) V(-1) s(-1).