The study of turbulence is very relevant to fluid mechanics. This complex and chaotic phenomenon has been under investigation for many years because it is directly related to the energy efficiency of various engineering applications, such as airplanes and long pipelines, for examples, Several flow visualization techiniques have been developed over the years to help the studies, among them the Tomographic Particle Image Valocimetry as Knoen as tomo-PIV. Using this method, it is possible to obtain a theree-dimensional flow velocity field, being able to assess all spacial derivatives. In this study, the tomo-PIV techinique was applied in a water turbulent flow inside a square section duct in order to obtain the theree-dimensional velocity field. Since this is a recent experiment in Brazil, a thorough understanding of the system and procedure used are important to promote similar future studies, A test section was specially adapted to reach the needs of present experiment. The results of the present work has demonstrated the succesfully application of tomo-PIV techinique. The obtained velocity fields displayed similiar acuracy to the literature. Moreover, this research presents a wide literature review on the techinique, outlining the basic principles, relevant equations, algorithms involved and main system elements.