The propagation of LaMnO3 laser ablation plume in oxygen background has been investigated using fast photography of overall visible plume emission and time-resolved optical emission spectroscopy. The plume expansion was studied with ambient oxygen pressures ranging from vacuum level to 100 Pa. Free-expansion, splitting, sharpening and stopping of the plume were observed at different pressures and time delays after the laser pulse. Time-resolved optical emission spectroscopy showed that oxides are mainly formed through reaction of the atomic species ablated from the target with oxygen in the gas-phase. These reactions mainly affect the content of lanthanum oxide in the plume, while emission of manganese oxide is barely observed in all the range of pressure investigated. (c) 2005 Elsevier B.V. All rights reserved.