The epoxidation of secondary high molecular weight guayule rubber (SHMWGR) and subsequent ring opening with fluoroacids to give hydroxyfluoroesters (FGR) is reported. Structural characterization was performed with FTIR; H-1-, C-13-, and F-19-NMR; and DSC. The percent epoxidation was quantitatively determined by H-1-NMR. it was noted that the glass transition temperatures (T-g) of the FGR polymers increased with increasing fluoro acid content; however, reactions with longer chain, highly fluorinated acids lowered the T-g.