The collisional behavior of NCO[(X) over tilde(0,n,0)] in specific vibronic states in the gas phase has been investigated in the time-domain by laser-induced fluorescence (LIF) on transitions within the system NCO((A) over tilde (2) Sigma(+)-(X) over tilde (2) Pi). The NCO radical was generated by the infrared multiphoton dissociation (IRMPD) of phenyl isocyanate (PhNCO) by means of a TEA-CO2 laser operating on the 9R24 line at lambda=9.25 mu m with subsequent monitoring of the vibronic levels of the (X) over tilde state, characterized by Renner-Teller coupling, in the presence of N-2, O-2, NO, CO2, N2O, SO2, and PhNCO itself. The states probed were as follows : (00(1)0)(2) Pi(3/2), (00(1)0)(2) Pi(1/2), (01(0)0)mu(2) Sigma(+), (01(2)0)(2) Delta(5/2), (01(2)0)(2) Delta(3/2), (02(1)0)mu(2) Pi(3/2,1/2), (02(3)0)(2) Phi(7/2), and (02(3)0)2 Phi(5/2). Various pairs of spin-orbit states were found to be tightly coupled kinetically. Thus, the time-evolution of the pairs of vibronic states (00(1)0)(2) Pi(3/2) and (00(1)0)(2) Pi(1/2); (01(2)0)(2) Delta(5/2), and (01(2)0)(2) Delta(3/2); (02(3)0)(2) Phi(7/2) and (02(3)0)(2) Phi(5/2) were found to be equal, yielding an effective local equilibrium within these spin-orbit components within experimental error. Further, states such as NCO(01(0)0) and NCO(01(2)0) were characterized by relatively long decay profiles in the presence of molecules such as CO2 and O-2 where the contribution of rotational quenching to the overall decay process could be neglected. By contrast, NCO(02(1)0) and NCO(02(3)0) were removed on significantly faster time scales on collision with SO2. : (00(1)0)(2) Pi(3/2), (00(1)0)(2) Pi(1/2), (01(0)0)mu(2) Sigma(+), (01(2)0)(2) Delta(5/2), (01(2)0)(2) Delta(3/2), (02(1)0)mu(2) Pi(3/2,1/2), (02(3)0)(2) Phi(7/2), and (02(3)0)2 Phi(5/2). Various pairs of spin-orbit states were found to be tightly coupled kinetically. Thus, the time-evolution of the pairs of vibronic states (00(1)0)(2) Pi(3/2) and (00(1)0)(2) Pi(1/2); (01(2)0)(2) Delta(5/2), and (01(2)0)(2) Delta(3/2); (02(3)0)(2) Phi(7/2) and (02(3)0)(2) Phi(5/2) were found to be equal, yielding an effective local equilibrium within these spin-orbit components within experimental error. Further, states such as NCO(01(0)0) and NCO(01(2)0) were characterized by relatively long decay profiles in the presence of molecules such as CO2 and O-2 where the contribution of rotational quenching to the overall decay process could be neglected. By contrast, NCO(02(1)0) and NCO(02(3)0) were removed on significantly faster time scales on collision with SO2.