This study investigates the influence of raw materials, synthesis routes, and thermal treatment on the physicochemical properties of cadmium yellow (CdS-based) pigments, with particular emphasis on structure–property relationships and process conditions. Cadmium chloride, sulphate, nitrate, and carbonate were used as cadmium precursors, while sodium sulphide and elemental sulphur served as sulphur sources. Pigments were synthesized via two approaches: precipitation from aqueous solutions under controlled pH conditions, followed by drying (90°C) and calcination (600°C), and a direct solid-state reaction of cadmium carbonate with sulphur at 600°C. Comprehensive characterization was carried out using CIELab colour analysis, atomic absorption spectrometry (AAS), thermogravimetric methods (TG/DTG/DTA), X-ray diffraction (XRD), FTIR spectroscopy, and XPS analysis. The results demonstrate that both precursor selection and processing conditions significantly affect pigment composition, crystallographic structure, and optical properties. Thermal treatment promotes the transformation of CdS into a stable hexagonal phase and induces the formation of secondary phases (e.g., sulphates, carbonates), which influence colour parameters and thermal stability. From a materials engineering perspective, the precipitation method in an acidic environment yields pigments of higher purity and well-developed hexagonal CdS structure, resulting in improved optical performance. However, from a process engineering standpoint, the direct solid-state synthesis route offers a simplified and scalable alternative with reduced processing steps and competitive material properties. The findings provide valuable insight into the design and optimization of CdS-based pigments for high-temperature applications