Nowadays, various technological treatments are applied to enable reinforcement of metallic materials, with aim to enhance their surface properties at favourable costs. Thermochemical and thermomechanical treatment, together with deposition of special surface layers, play a key role in the automotive, electrical, and aerospace industries. The aim of the textbook is to provide information on most frequently used technological processes for improving functional properties of metals and metallic alloys (thermochemical treatment, surface hardening, formation of special surface layers, surface nanocrystallization) and applicability of each individual process. The theoretical knowledge is complemented and illustrated by examples of material microstructures and processed components. The textbook is designed for high school and college students with a basic technical background in Surface Engineering, Materials Engineering and Technology of Materials Production. The information contained may be also useful for engineering professionals – designers, technologists, R&D and testing laboratories staff, dealing with metallic materials, manufacturing technology, component testing, and quality management.