The book is evolved out of a lecture course given at the Norwegian Science and Technology since 1998, and will provide a description of the fundamentals of chemical sensors, with an emphasis on basic principles. Due attention will be paid to classical topics in the field but, at the same time, this book will highlight contemporary challenges. It will include recent advances caused by the advent of new concepts, materials and technologies, for example micro-electromechanical systems, nanotechnology and nanomaterials, quantum dots, bio-composites, molecular imprinting, lab-on-a-chip and microfluidics. Provisional TOC: Introduction; Chemical recognition general features; Theoretical principles an overview; Potentiometric sensors; Field effect devices-based chemical sensors; Amperometric sensors; Electrochemical impedance spectrometry; Fibre optic chemical sensors; piezoelectric and acoustic devices; Solid-state gas sensors; Applications of chemical sensors and biosensors; Advanced topics; Appendix laboratory exercises. The book will also contain mathematical calculation exercises (with solutions), and a guide to Laboratory exercises as an inspiration for experimental projects. An accompanying website will contain colour illustrations and Powerpoint slides.