Hydrogen (H2) detectors are important tools to ensure the safety in H2 production/storage/transportation/use and also monitor many H2-related physiochemical processes in industrial or medical practices. Ideal H2 detectors should not only have high detection performance (e.g., high sensitivity and selectivity) but also possess low power-consumption, high compactness, simple fabrication using low-cost materials, and ease of instrumentation that can be easily handled and operated. In this work, nanoporous composites by simply reducing palladium (Pd) precursors to the surface of halloysite nanotubes (HNTs) were developed and optimized for the development of a resistive H2 detector. The detector was prepared by depositing solution droplets of Pd/HNT with an optimal mass concentration on an interdigitated microelectrode surface of 1 cm × 1 cm and then drying it at 65 °C. The developed H2 detector exhibited reliable H2 detection, achieving low limit H2 detections of 27 ppb and <10 ppm in both N2 and air, respectively. It also presented high selectivity, differencing H2 from other interfering gases such as CO2 and CH4, and demonstrated stability in its response from room temperature to 50 °C. We attribute the characteristics of the detector performance to the nature of Pd/HNT composites (large surface, high porosity, specific reaction of Pd to H2, etc.). Given its high detection performance, simple resistance read-out, and ease of fabrication, it is believed that the developed detector will have broad applications in the H2 energy industry and many other H2-related industrial and medical procedures.