Reactions of trans-di-( n-pyridyl)ethylenes ( n,n′-DPEs, n,n′ = 2,3,4) and 4,4′-bipyridyl (BPY) following excitation by UV laser pulses were studied at room temperature in organic solvents. Upon direct laser excitation a triplet was observed for BPY (λ max = 340 nm) and 2,2′-DPE (λ max = 360 nm) but not for 3,3′-DPE and 4,4′-DPE. The transient of 4.4′-DPE in 2-propanol (λ max = 455 nm) and a second transient of BPY (λ max = 370 nm) are assigned to radicals (half-life ⩾ 0.1 ms) of the type H-DPE • and H-BPY • respectively. The structure of H-DPE • is that of a hydrogen atom adduct to one of the nitrogens. The radicals are formed by hydrogen atom abstraction from the solvent involving the excited n,π* singlet state of trans-4,4′-DPE and the n,π* triplet state of BPY.