We present a study of the collisional quenching of electronically excited calcium atoms, Ca[4s4p(3PJ)], 1.885 eV above the 4s2(1S0) ground state, by a range of added gases. Ca(4 3P1) was generated by repetitive pulsed dye-laser excitation at λ= 657.3 nm [Ca(4 3P1)â†� Ca(4 1S0)] of calcium vapour in equilibrium with solid calcium at elevated temperatures (1000 K) in a slow flow system, kinetically equivalent to a static system. Following rapid Boltzmann equilibration within the 4 3PJ manifold, the time-resolved forbidden emission, 4 3P1→ 4 1S0+hν(λ= 657.3 nm), was monitored in the presence of added gases using ‘pre-trigger photomultiplier gating’ and boxcar integration. The following absolute second-order quenching constants (kQ/cm3 molecule–1 s–1, 1000 K, errors 1σ) are reported: CO, 3.7 ± 0.5 × 10–13; NO, 3.2 ± 0.3 × 10–13; CO2, 3.1 ± 0.3 × 10–13; N2O, 6.5 ± 0.5 × 10–13; NH3, 2.5 ± 0.3 × 10–13; CH4, 5.4 ± 0.4 × 10–13; CF4, 1.9 ± 0.2 × 10–13; C2H2, 1.4 ± 0.2 × 10–13; C2H4, 2.3 ± 0.3 × 10–13; C6H6, 6.0 ± 0.2 × 10–12. Where possible these data are compared with those derived from other decay measurements in which Ca(4 3PJ) was generated by dye-laser excitation and monitored either via time-resolved atomic resonance absorption spectroscopy or by phase-shift techniques. The absolute rate constants are compared with analogous data for Mg(3 3PJ)(2.71 eV) and discussed, where appropriate, in terms of orbital correlation and in relation to data from atomic beams which describe chemiluminescence from product states.