Background <p>Short life span of soybean seed under ambient storage conditions is a serious challenge for crop production and germplasm maintenance. There are scarce reports on linkage mapping of QTLs for seed longevity, and the molecular mechanisms remain largely unclear. The study aimed to develop a biparental recombinant inbred lines (RIL) mapping population suitable to examine seed and seed coat properties contributing to seed viability as well as seed yield and yield traits. An RIL population from JS 93 − 05 × Local Black Soybean (LBS) cross was developed and evaluated for seed and seed coat properties at F₅ generation providing a robust resource for QTL mapping and breeding for improved seed longevity.</p> Results <p>Comprehensive assessment of RIL population for seven seed and seed coat properties including water permeability and seedling vigor index revealed broad and continuous variation in quantitative traits. The mean, range and coefficient of variation of these 7 seed traits indicated the presence of high variability in the RIL population. Distinct segregation in qualitative seed coat features, such as seed coat colour, hilum colour and seed coat lustres further underscore the involvement of these traits on seed longevity. RILs with black seed coats exhibited an association between higher seed coat content and reduced water permeability, suggesting pigmentation mediated enhanced seed longevity. Furthermore, RIL lines with low-permeability displayed greater seed coat thickness, reinforcing the role of physical seed coat traits in regulating water uptake.</p> Conclusions <p>The developed biparental F₅ mapping population demonstrates extensive genetic and phenotypic diversity for seed and seed coat traits, offering a valuable resource for mapping loci associated with seed longevity.</p>