Book excerpt: This book presents a state-of-the-art summary and critical analysis of work recently performed in leading research laboratories around the world on the implementation of metal oxide nanomaterial research methodologies for the discovery and optimization of new sensor materials and sensing systems. The book provides a detailed description and analysis of (i) metal oxide nanomaterial sensing principles, (ii) advances in metal oxide nanomaterial synthesis/deposition methods, including colloidal, emulsification, and vapor processing techniques, (iii) analysis of techniques utilized for the development of low temperature metal oxide nanomaterial sensors, thus enabling a broader impact into sensor applications, (iv) advances, challenges and insights gained from the in situ/ex situ analysis of reaction mechanisms, and (v) technical development and integration challenges in the fabrication of sensing arrays and devices.