The kinetics of the AlO + O-2 reaction system has been studied in a high-temperature fast-flow reactor (HTFFR) from 7 to 100 mbar. The relative AlO concentrations were monitored by laser-induced fluorescence at the B-2 Sigma-X(2) Sigma and (CII)-I-2-X(2) Sigma transitions. Below about 1000 K the AlO consumption is pressure-dependent, that is, leading initially to AlO3, with log k(305-1010 K) = -25.36 - 1.69 log(T/K) cm(6) molecule(-2) s(-1), as obtained by weighted linear regression. At higher temperatures the system becomes pressure independent with AlO2 and O as the likely products. For this process k(1200-1690 K) = 7.7 x 10(-10) exp(-10008 K/T) cm(3) molecule(-1) s(-1). The accuracy estimates are discussed in the text. The reactions are suggested to proceed through an OAlOO addition complex of similar structure as identified in solid matrices.