Hydrogen (H2) is attracting attention as a renewable energy source in various fields. However, H2 has a potential danger that it can easily cause a backfire or explosion owing to minor external factors. Therefore, H2 gas monitoring is significant, particularly near the lower explosive limit. Herein, tin dioxide (SnO2) thin films were annealed at different times. The as-obtained thin films were used as sensing materials for H2 gas. Here, the performance of the SnO2 thin film sensor was studied to understand the effect of annealing and operating temperature conditions of gas sensors to further improve their performance. The gas sensing properties exhibited by the 3-h annealed SnO2 thin film showed the highest response compared to the unannealed SnO2 thin film by approximately 1.5 times. The as-deposited SnO2 thin film showed a high response and fast response time to 5% H2 gas at 300 °C of 257.34% and 3 s, respectively.
