The first observation of laser-induced fluorescence of the SO free radical is described. Using excitation with pulses of narrow-band laser radiation near 260 nm, the A3Π states of SO have been excited. Doppler-limited laser excitation spectra of SO (A3Π–X3Σ–) are reported. The radiative lifetimes τ0 of quantum resolved (v′, J′) state of the A3Π(1) and A3Π(0) states are reported; the mean value of τ0 was (16.4 ± 1.4)µs for v′= 1. Rate constants for quenching the A3Π(1) state of SO are also reported. A proposal for an SO (A–X) electronic transition laser, giving near u.v. and visible (blue) output, is discussed.