ABSTRACT: Humidity is a very common component in our environment, measurements and/or control of humidity is important not only for human comfort but also for a broad spectrum of industries and technologies. The constructive design of a good humidity sensor is a rather complicated topic, because high performance humidity sensors claim many requirements, including linear response, high sensitivity, fast response time, chemical and physical stability, wide operating humidity range and low cost. Humidity sensors are important devices that can be used to measure and monitor environmental humidity. The magnetic core-shell (Mg(x)Fe(1-x)O/SiO2) nanoparticle has shown great humidity sensing properties. There has been increasing interest in the design and fabrication of magnetic core-shell nanoparticle, due to their humidity sensing application. The present work deals with synthesis and characterization of Mg(x)Fe(1-x)O (x=0.1,0.2, 0.4) by echo friendly chemical combustion synthesis, Mg(x)Fe(1-x)O/Sio2 magnetic core-shell nanoparticle by chemical precipitation and humidity sensing application of magnetic core-shell nanoparticle. Keywords: XRD, TG-DTA, Particle Analyzer, FTIR, SEM, EDS, TEM