Objective: This study was aimed to obtain a new excipient that can be used as a polymer matrix for the formulation of controlled release dosage forms.Methods: This study used coprocessing and crosslinking methods on amylose and xanthan gum (XG) to obtain a new excipient that can be usedfor controlled release matrix of pharmaceutical dosage forms. The coprocessing step was conducted by drum drying, and the crosslinking step wasprepared using 6 and 12% sodium trimetaphosphate (STMP). The produced novel excipients were characterized in terms of infrared (IR) spectrum,substitution degree, moisture content, swelling index, and gel strength.Results: Our results showed that amylose–XG excipients crosslinked using 6% STMP have greater gel strength and better swelling indexes thanexcipients crosslinked using 12% STMP. All coprocessed excipients exhibited no differences in their IR spectra, whereas the crosslinked excipientsdid, indicating a structural change due to the addition of phosphate groups. Crosslinking amylose–xanthan-coprocessed excipients using 6% STMPproduced degrees of substitution (DSs) of 7–8 phosphates per 100 monomeric subunits. The excipients had a moisture content of 8.21–12.85%, andthe pH of a 1% solution of excipients was 6.21–6.43. In addition, the swelling index and gel strength of the excipient where both amylose and XG werecrosslinked together Were more than 1 where only amylose was crosslinked.Conclusion: The crosslinking amylose–xanthan-coprocessed excipient using 6% STMP is more suitable for use in controlled release dosage forms,particularly when the polymer ratio is 1:1.