<p>In Ziegler–Natta catalysts (ZNC), the thermal treatment applied during catalyst synthesis—commonly termed tempering (TMP)—exerts a decisive influence on catalytic efficiency and the properties of the resulting polymers. In this study, a series of catalysts were synthesized under systematically varied TMP conditions, comprehensively characterized, and subsequently employed in bimodal (BM) polymerization processes. The results demonstrate that both the TMP stage and duration profoundly affect titanium dispersion, textural properties, and catalytic performance. These structural modifications were reflected in distinct variations in catalytic activity (CA) and polymer particle morphology, particularly in particle size distribution (PSD) and wax formation. Polymerization experiments further revealed that optimized TMP conditions markedly enhanced catalyst productivity and stability, minimized wax generation, and improved polyethylene powder (PEP) quality, notably in terms of particle uniformity and bulk density. In contrast, TMP variations exerted negligible effects on the thermal and rheological properties of the final polyethylene. Thermal and rheological analyses confirmed that crystallinity, melting behavior, and viscoelastic profiles remained consistent across all samples. Collectively, these findings establish TMP optimization as an effective strategy to enhance catalyst performance without compromising intrinsic material properties, reinforcing its industrial relevance in polyethylene manufacturing.</p> Graphical Abstract <p></p>