Cement manufacturing is indeed associated with several significant challenges such as energy intensity, greenhouse gas emissions, and is costly. To address these challenges, the construction industry seeks sustainable alternatives. This study explores the potential use of Breweries Dry Grain Ash (BDGA) as a partial replacement for ordinary Portland cement (OPC) in mortar production. Various mixtures were prepared with different proportions of BDGA (0%, 5%, 10%, 15% and 20%) while maintaining a constant water-to-cement ratio. By utilizing a combination of TGA and DTA, the study aims to provide a comprehensive understanding of BDGA’s potential as a sustainable additive in mortar production. These techniques allow me to delve into the physical, chemical, thermal, and micro structural aspects of mortar mixes containing BDGA, thereby evaluating its suitability in terms of performance, sustainability, and economic feasibility compared to conventional OPC-based mortars. BDGA exhibited pozzolanic properties and had a porous surface with irregular and angular edges. The results showed that the workability and setting time decreased and quantity of water required for attaining normal consistency increased as the BDGA content increased. The compressive strength of the mortar increased by for 14.5% with 10% BDGA and 5.6% with 5% BDGA compared to the control mix. BDGA5 and BDGA10 significantly improved the compressive strength, bulk density, and ultrasonic pulse velocity, especially in older mortars. Micro structural analysis revealed high density in BDGA5 and BDGA10 mixtures. Additionally, the thermal stability of BDGA increased with higher replacement percentages, and showed little loss of mass due to increasing temperature. Key Words: Brewiers dry grain ash; Supplementary Cementitious Materials; Fresh Properties; Mechanical Properties; Mortar