The doping of Mylar (R) film (composed of semi-crystalline poly(ethylene terephthalate)) with small-molecule electron traps results in a high-quality dielectric film with excellent radiation tolerance. This paper, the first of two, investigates the doping process as small molecules are implanted into the film from a solution of ethylene glycol over time. A series of fluorenone-based dopants are investigated, functionalized by nitro or cyano groups. The concentration of dopant in the Mylar (R) is a strong function of time, temperature, and solution concentration. Doping is ineffective below the glass transition temperature of the polymer. The chemical functionality of the dopant had a strong effect on the doping process, with additional nitro or cyano groups leading to enhanced film concentrations. (C) 2008 Published by Elsevier Ltd.