The　lead-free　double　perovskite,　increasingly　sought　for　optoelectronic　pursuits,　is　distinguished　by　its　notable　stability,　optical　properties,　and　non-toxic　characteristic.　An　extensive　inquiry　into　the　structural　and　photoelectric　properties　of　Cs2NaBiCl6　at　heightened　temperatures　was　undertaken　using　experimental　evaluations　and　theoretical　computations.　The　compound　Cs2NaBiCl6,　synthesized　using　a　hydrothermal　technique,　was　confirmed　via　various　analytical　methods.　Advanced　techniques　such　as　high-temperature　X-ray　diffraction,　X-ray　fluorescence,　X-ray　photoelectron　spectroscopy,　and　selected　area　electron　diffraction　were　employed　for　the　investigation　of　its　crystal　structure.　Further　investigation　of　microstructure　was　undertaken　using　electron　microscopes.　High-temperature　luminescence　stability　disclosed　a　high　exciton　binding　energy　of　326　meV.　The　Huang-Rhys　factor　(6.4)　denotes　a　robust　electron-phonon　coupling　effect　and　facile　formation　of　self-trapped　excitons　(700　nm).　Applied　first　principles　render　valuable　insight　into　structural　and　photoelectric　nuances,　notably　at　escalated　temperatures.　Cs2NaBiCl6　as　an　indirect　bandgap　semiconductor　and　details　the　experimental　and　theoretical　bandgap,　which　exhibits　an　increasing　trend　before　subsequently　declining　at　elevated　temperatures.　These　results　strongly　support　the　material＇s　high-temperature　stability,　emphasizing　its　applicability　in　applications　such　as　rare-earth-doped　phosphors.　The　dynamic　stability　of　the　material,　evidenced　by　its　mechanical　performance,　further　underscores　its　potential　for　application　in　photoelectric　devices.　©　2023　Elsevier　B.V.