This book delves into X-ray fluorescence (XRF) spectroscopy, focusing on instrumental developments and data analysis methods employing chemometrics for environmental applications. The integration of information from multiple datasets is gaining an increase in attention and significance in the environmental sciences. In this book, the contributors provide an up-to-date treatment of the most extensively used chemometric methods for predicting and interpreting spectroscopic data in environmental applications. This book describes recent trends in XRF spectroscopic methods, encompassing energy-dispersive and wavelength-dispersive X-ray fluorescence, synchrotron radiation-based XRF, micro-XRF, and total reflection-XRF. It delivers a comprehensive discussion on X-ray detectors and associated imaging applications, along with an exploration of the analytical capabilities of these methods, including detection limits, accuracy, and precision in measurements for environmental samples. Furthermore, this book discusses the numerous advantages and limitations of these techniques, highlighting the latest developments in algorithms based on machine learning, neural networks, and AI for spectroscopic data interpretation. This book caters to researchers across various branches of science and technology, aiming to introduce them to modern techniques coupled with advanced data analysis methods. It serves as a valuable reference for those engaged in XRF spectroscopy techniques, hyphenated XRF spectroscopic techniques, and the characterization of biomolecular systems and environmental samples.