The use of bio-based Phase Change Materials (bio-PCM) is an effective mean to enhance the building's Thermal Energy Storage (TES) capacity with low-cost and eco-friendly materials. The present study encompasses the results of thermal, physico-chemical and mechanical characterizations of a novel composite bio-PCM developed in the laboratory to improve the thermal comfort in the building's indoor environments. We tested a non-cocoa Vegetable Fat (VF) recovered from confectionery manufacturing industry. The VF is incorporated into a mineral board prepared from Natural Clay (NC) and Cellulose Fibers (CF). Phase change temperatures and TES capacity of the composite at melting and freezing cycles are measured with Differential Scanning Calorimetry (DSC) to be at 34.83 degrees C, 22.34 degrees C and 60.41 J/g, 62.39 J/g respectively. The Scanning Electron Microcopy (SEM) showed that the VF was evenly distributed into the microstructure of the mineral board. Results of thermal stability tests (more than 2000 cycles) confirmed that the composite bio-PCM is thermally and chemically stable. The compressive strength of the supporting material was slightly reduced after the incorporation of the bio-PCM, but it remains within the accepted limits for non-structural building applications. This research on thermal and mechanical properties has revealed that this homemade PCM panel could be a potential candidate for an application in buildings of hot and dry climates.