As the demand for hydrogen sensors and hydrogen analyzers grows, the accurate, fast response hydrogen detection is critical especially in medical diagnostics. Here, hydrogen sensor was developed using titania nanotubes array as the sensing element. The effect of the nanotubes pore size and the operating temperature on the sensitivity of the sensor were investigated. Nanotubes with average pore size ranging from 58 nm to 75 nm were fabricated by anodization process. The sensor was tested at two different operating temperatures and varying hydrogen concentration from 10 ppm to 100 ppm. The sensitivity of the sensor was found to be significantly higher at the temperature of 300°C as compared to 200°C. For both temperatures, titania nanotubes with smaller pore size showed higher sensitivity to hydrogen compared to the larger ones with detection as low as 10 ppm of hydrogen. © 2012 American Institute of Physics.