Time-resolved attenuation of the atomic emission transition C(33P°J→23PJ) at 166 nm has been used to study the reactions of C(23PJ). The decay of this atom, following its generation by the vacuum ultra-violet flash photolysis of carbon suboxide, has been monitored directly in the presence of a number of gases. The following rate data for 300 K have been obtained: C(23PJ)+ NO →CN + O, k= 7.3±2.2 × 10–11 cm3 molecule–1 s–1, C(23PJ)+ O2→CO + O, k= 3,3±1.5 × 10–11 cm3 molecule–1 s–1, C(23PJ)+ N2O →CO + N2, k= 2.5±1.6 × 10–11 cm3 molecule–1 s–1, or CN + NO, C(23PJ)+ H2O →CO + H2k⩽3.6 × 10–13 cm3 molecule–1 s–1, or CH2O, C(23PJ)+ CO2→2CO, k≤ 10–14 cm3 molecule–1 s–1, C(23PJ)+ CH4→C2H4, k < 2 × 10–15 cm3 molecule–1 s–1, C(23PJ)+ N2+ M →CN2+ M, k= 3.1±1.5 × 10–33 cm6 molecule–2 s–1(M = Ar), C(23PJ)+ H2+ M →CH2+ M, k= 7.1±2.5 × 10–32 cm6 molecule–2 s–1(M = He), C(23PJ)+ CO + M →C2O + M, k= 6.3±2.7 × 10–32 cm6 molecule–2 s–1(M = He).