Industrial plants have an abundance of complex and confined areas that require systematic inspection. Maintenance work is necessary to ensure reliability and safety. In many cases, due to either size limitations or high danger, access is impossible to humans. Current inspections require long and costly dismounting or safety procedures. Robotic inspection could be a convenient solution to overcome the lack of accessibility and safety for human inspectors. In the energy industry for instance, where downtime can cost millions of dollars per day, dedicated and agile robots may pursue inspection faster than humans, thus reducing the duration of overhaul. Additionally, robotic inspection may offer higher repeatability and reliability compared to human inspection. Distraction or simply boredom caused by repetitive tasks may result in an incomplete or failed inspection. Moreover, social costs and the hardness of working in an unfriendly or even toxic environment may be reduced. This work focuses on adhesion analysis, integration and mobility extension of miniature climbing robots for industrial applications. Existing solutions were carefully analysed in order to propose an innovative technology and methodology to be used in the design and implementation of these robots. The main objective was to increase the availability, capability and use of mobile robots for inspection in complex industrial environments. Due to the reduced dimensions of the industrial areas to be inspected, in some cases less than 25 mm, miniaturisation of the robot was required, as well as high mobility in 3D complex environments. Climbing ability is enhanced by improving adhesion techniques and their synergy with locomotion. Ferromagnetic environments are common in industrial facilities. Since magnetic adhesion is superior to other methods, a major effort of this work has been devoted to methodically understand and improve the use of permanent magnets as adhesion and magnetization devices integrated into miniature climbing inspection robots. Implementation of the magnetic adhesion was achieved in different magnetic climbing robots with locomotion principles such as wheels, caterpillars or feet. An innovative obstacle passing mechanism was proposed with the Cy-mag3D robots family. A proposed approach is the use of a Magnetic Switchable Device (MSD) as an adhesive and magnetizing device for inspection robots. Results show that the energy efficiency of MSDs is higher when compared to the vertical mechanical detachment of a system with permanent magnets or an electromagnetic system. MSDs have been used in TUBULO, an inchworm for visual inspection of boiler tubes of 25 mm in diameter, and TREMO, a climbing inchworm for visual inspection of complex ferromagnetic environments. A novel MSD configuration was proved adequate to perform Magnetic Particle Inspection (MPI). This work proposes novel solutions to realise miniature magnetic climbing robots dedicated to inspection. The proven results go beyond the anterior state of the art. Accordingly, inspection robots may move with versatility in industrial environments. The outcome of this work opens new perspectives for the use of mobile climbing robots with direct application in industrial inspection.