This paper presents a comprehensive evaluation of the physical, mechanical, and thermal properties of polycrystalline titanium diboride (TiB₂) with a focus on how these properties depend on density and grain size. The study determines a coherent set of trend values for TiB₂ properties under specific conditions: a mass fraction of TiB₂ ≥ 98%, a density of (4.5 ± 0.1) g/cm³, and a mean grain size of (9 ± 1) μm. The research builds on previous studies of alumina and silicon carbide, where processing procedures were well-controlled, allowing for smaller batch-to-batch variations. For TiB₂, however, processing is less refined, leading to greater variability, making it essential to establish consistent trend values for its properties. The study examines the elastic modulus, shear modulus, Poisson's ratio, and bulk modulus of TiB₂, showing that these properties are influenced by temperature and density. The elastic modulus increases with density and is linearly related to the measured density. The shear modulus also varies linearly with temperature. The fracture strength of TiB₂ decreases with increasing grain size, and the optimal grain size for maximizing fracture toughness is between 5 and 10 μm. The hardness of TiB₂ is relatively insensitive to density and grain size, but the indentation size effect is observed, indicating that hardness depends on the applied load. The study also investigates the creep behavior of TiB₂ under sustained high-temperature loading, finding that the creep rate is influenced by temperature and stress. Friction and wear characteristics of TiB₂ are evaluated, showing that the coefficient of friction varies with temperature and sliding conditions. The wear coefficient is found to be (17 ± 4) × 10⁻⁴ at room temperature. The specific heat of TiB₂ increases with temperature, and the thermal diffusivity and thermal conductivity are determined using interpolation formulas. The study concludes that while there is significant variability in property values among different batches of TiB₂, trend values can be established based on microstructural statistics, providing a consistent framework for evaluating the material's properties.This paper presents a comprehensive evaluation of the physical, mechanical, and thermal properties of polycrystalline titanium diboride (TiB₂) with a focus on how these properties depend on density and grain size. The study determines a coherent set of trend values for TiB₂ properties under specific conditions: a mass fraction of TiB₂ ≥ 98%, a density of (4.5 ± 0.1) g/cm³, and a mean grain size of (9 ± 1) μm. The research builds on previous studies of alumina and silicon carbide, where processing procedures were well-controlled, allowing for smaller batch-to-batch variations. For TiB₂, however, processing is less refined, leading to greater variability, making it essential to establish consistent trend values for its properties. The study examines the elastic modulus, shear modulus, Poisson's ratio, and bulk modulus of TiB₂, showing that these properties are influenced by temperature and density. The elastic modulus increases with density and is linearly related to the measured density. The shear modulus also varies linearly with temperature. The fracture strength of TiB₂ decreases with increasing grain size, and the optimal grain size for maximizing fracture toughness is between 5 and 10 μm. The hardness of TiB₂ is relatively insensitive to density and grain size, but the indentation size effect is observed, indicating that hardness depends on the applied load. The study also investigates the creep behavior of TiB₂ under sustained high-temperature loading, finding that the creep rate is influenced by temperature and stress. Friction and wear characteristics of TiB₂ are evaluated, showing that the coefficient of friction varies with temperature and sliding conditions. The wear coefficient is found to be (17 ± 4) × 10⁻⁴ at room temperature. The specific heat of TiB₂ increases with temperature, and the thermal diffusivity and thermal conductivity are determined using interpolation formulas. The study concludes that while there is significant variability in property values among different batches of TiB₂, trend values can be established based on microstructural statistics, providing a consistent framework for evaluating the material's properties.