<p>Hydrolysis of reactive dyes is a well-recognised phenomenon that significantly affects dye fixation, chemical consumption, and effluent load in textile dyeing processes. Several advanced analytical techniques—such as ¹H-NMR, capillary electrophoresis, and high-performance liquid chromatography (HPLC)—have been developed to quantify this process. However, the complexity and resource-intensive nature of these methods limit their routine and widespread application. In this study, a simplified fixation-based method is proposed to estimate reactive dye hydrolysis. The method estimates dye hydrolysis based on the fixation percentage of pre-hydrolysed dye relative to a reference sample. Reactive dye hydrolysis was carried out at 60&#xa0;°C for 60&#xa0;min, with analysis conducted at 20-min intervals. A monofunctional reactive dye, Remazol Yellow RR, was used as a model compound, and the maximum hydrolysis determined by the proposed method was 61.6%. The same samples were also analysed by HPLC, which indicated that 80.5% of the dye had undergone hydrolysis under the same conditions. Although the fixation-based method reports lower hydrolysis values than HPLC, a strong linear correlation was observed between the two approaches, indicating that the proposed method can reliably capture relative changes in dye hydrolysis under the studied conditions. Furthermore, kinetic analysis demonstrated that the hydrolysis reaction follows a pseudo-first-order model. The proposed fixation-based method, therefore, offers a practical pathway for dyehouses to independently assess reactive dye hydrolysis behaviour using routine dyeing and spectrophotometric measurements. Future studies involving a broader range of reactive dyes, reactive systems, and dyeing conditions will be necessary to further evaluate the robustness and broader applicability of the proposed approach in practical dyehouse settings.</p>