<p>This study focuses on the comprehensive characterization of five major paddy straw varieties in Punjab—PB 370, PB 1121, PR 121, PR 126, and Pusa 44. Among the varieties, PB 370 exhibited the highest heating value (HHV) at 15.15&#xa0;MJ/kg, while PR 121 had the lowest ash content at 12.04%. Statistical analysis revealed that PR 126 exhibited statistically significant differences from all the varieties except PB 370 for ash content, whereas for HHV it showed significant differences from all other paddy straw varieties. Thermogravimetric analysis (TGA) was also performed to understand thermal degradation behavior at 10, 20, and 30&#xa0;°C/min. Based on the kinetic study, Pusa 44 had the highest activation energy at 145&#xa0;kJ/mol, and the lowest was observed for PR 126 at 108&#xa0;kJ/mol. FTIR analysis confirmed the presence of silica in the form of the Si–O-Si group in the 590–785&#xa0;cm⁻¹ range for all the varieties. XRD results also confirmed the presence of silicon oxide within the 2<i>θ</i> of 15–30° range in the ash sample at 550&#xa0;°C, emerging as the most predominant constituent relative to others. High levels of potassium, a critical alkali metal, were observed during EDS analysis in PB 1121 (20.4%), PR 126 (14.7%), and Pusa 44 (14.6%). Also, combustion ion chromatography revealed that PR 126 exhibited the highest concentrations of chloride (5034.50&#xa0;mg/kg), bromide (129.80&#xa0;mg/kg), and sulfur (2210.60&#xa0;mg/kg) but the lowest fluoride (18.90&#xa0;mg/kg) among all the paddy straw varieties studied. Interestingly, it was also observed that the duration of the crop has a significant positive correlation with the HHV and fluoride concentration of the paddy varieties. These findings provide crucial insights into the physicochemical properties of paddy straw varieties, highlighting their potential for energy and material valorization while addressing environmental concerns.</p> Graphical Abstract <p></p>