An optical oxygen sensor based on the phosphorescence quenching of platinum octaethylporphyrin (PtOEP) immobilized in a new fluoropolymer, poly(isobutyl methacrylate-co-tetrafluoropropyl methacrylate) (poly-IBM-co-TFPM) film was developed. The phosphorescence intensity of PtOEP in poly-IBM-co-TFPM film decreased with increase in oxygen concentration. The ratio I-0/I-100 was used to express the sensitivity of the sensing film, where I-0 and I-100 represent the detected phosphorescence intensities from a firn under argon-saturated and oxygen-saturated conditions, respectively. The I(0)l(100) value of PtOEP immobilized in poly-IBM-co-TFPM film was estimated to be 86.4 and large Stern-Volmer constant, K-SV obtained from the slope of the Stern-Volmer plot ((I-0/I) - 1 = K-SV [O-2]; where I-0, I and [O-2] are phosphorescence intensities in the absence and presence of oxygen and oxygen concentration in % in gas phase, respectively) was obtained to be 0.858(-1) compared with PtOEP immobilized in polystyrene film (I-0/I-100 = 4.5; K-SV = 0.035%(-1)). The times for the phosphorescence intensity changes of PtOEP immobilized in poly-IBM-co-TFPM film when the gas phase is changed from 100% argon to 100% oxygen and from 100% oxygen to 100% argon were 6.1 and 45.3 s, respectively. These results indicate that PtOEP immobilized in poly-IBM-co-TFPM film represents a highly oxygen sensitive device. (C) 2001 Elsevier Science B.V. All rights reserved.