Hexaethylene (C12E6) and octaethylene (C12E8) glycol dodecyl ethers in dilute aqueous solutions, with or without poly(acrylic acid) (PAA), were studied by steady-state fluorescence and time-resolved fluorescence quenching methods, using pyrene as probe and dimethylbenzophenone as quencher. The polarity parameter (I-1/I-3) pointed out a critical aggregation concentration lower than the critical micelle concentration of the surfactant. On polymer addition, the fluorescence lifetime increased, indicating that the polymer wraps around the micelle-like clusters of surfactants. The aggregation numbers of clusters were smaller than those of free micelles. For 10.2 mM PAA and surfactant concentrations higher than around 1 mM, free micelles appeared in solution, but cluster formation continued until polymer saturation. At the surfactant concentration selected (1 mM for C12E6 and 0.8 mM for C12E8) and over the temperature range chosen (8-45 degrees C for C12E6 and 8-60 degrees C for C12E8), the presence of polymer does not very much affect the temperature dependence of aggregation number.