A novel in situ steady state fluorescence experiment was performed for studying slow release processes in gels formed by free radical cross-linking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate. Gels were prepared at 75 degreesC with pyrene (P-y) as a fluorescence probe. After drying these gels, slow release experiments were performed in various solvent with different molar-volume, V and Solubility parameters, delta at room temperature by real-time monitoring of the P-y nuorescence intensity. Slow release diffusion coefficients (D) were measured and found to be in between 0.23 x 10(-6) and 2.06 x 10(-6) cm(2) s(-1) depending on the solvent used. (C) 2002 Elsevier Science Ltd. All rights reserved.