Plant gas exchange properties, including maximum carboxylation rate of Rubisco (Vcmax), maximum electron transport rate (Jmax), light compensation point (LCP), light saturation point (LSP), maximum photosynthetic rate (Amax), and apparent quantum yield (Aqy), are key determinants of photosynthetic efficiency. This study evaluates these gas exchange characteristics in selected plant species at UTHM using a portable photosynthesis system (LICOR). The A/Ci and A/Q response curves demonstrated that photosynthetic assimilation increased with higher CO₂ concentrations and light intensity until saturation was reached. Among the studied species, Spathodea campanulata exhibited the highest Vcmax (52.14 ± 0.005 µmol CO₂ m⁻2 s⁻1) and Jmax (104.46 ± 0.011 µmol CO₂ m⁻2 s⁻1), whereas Rhapis excelsa recorded the highest LCP (69.60 ± 0.067 µmol photons m⁻2 s⁻1) and Costus spicatus displayed the highest LSP (1576.69 ± 0.173 µmol photons m⁻2 s⁻1). These findings suggest that different plant species exhibit varying photosynthetic responses to environmental factors, with higher light and CO₂ concentrations enhancing their carbon sequestration potential. The results underscore the importance of selecting species with higher photosynthetic assimilation rates for optimizing carbon absorption and supporting sustainable environmental managements.