The present study reports on the synthesis of nano ZnO using two different processes i.e., biological (green synthesis) and chemical synthesis (solution combustion technique). The prepared materials were characterized by microscopy and spectroscopy techniques, such as Field emission scanning electron microscope (FE-SEM), UV–visible spectroscopy, X-Ray Diffraction (XRD) and Fourier Transform-Infrared (FT-IR) spectroscopy. The two synthesized materials were analyzed and their liquefied petroleum gas (LPG) sensing properties to their sensing characteristics were compared, to highlight the suitable one for chemiresistor. The dynamic gas sensing analysis, sensitivity and resistance were studied. For optimization, sensing characterization was monitored at various operating temperatures in different LPG concentration. Eventually, we found out that the green synthesis route, to fabricate sensor devices is more advantageous as it is cost-effective, eco-friendly and simple. © 2016 Elsevier Ltd