Introduction: When selecting materials for the manufacture of devices used in orthotics and prosthetics, it is necessary to consider some of their basic properties and processing. The properties of orthotic materials, among other things, affect the quality of the patient's life, the thermal conductivity and the permeability to water vapour. Purpose: The purpose of this thesis is to choose some of the most common materials used in orthotics and determine the differences in terms of permeability to water vapour and the thermal conductivity of these materials. Methods: The thermal conductivity was determined in accordance with the requirements of EN 12667: 2002, while the water vapour’s permeability was measured according to DIN EN 7783:2012. For measuring the thermal conductivity a special device was used, made from two sheets at different temperatures, between which the sample material was inserted. From the measured values, the heat conductivity of the material was calculated. For measuring the permeability with respect to water vapour a measuring cup was used. The speed of migration of the water vapour was determined gravimetrically, while the amount of water vapour at room temperature was measured per unit time passing from the measuring cup with a higher relative humidity through the sample into a space with a lower relative humidity. Based on calculations we obtained the values of the permeability to water vapour for a particular material. Results: During the experiments we tested different orthotic materials, i.e., the thermoplastic polymers: polyethylene, polypropylene and their copolymers, foamed polymers with the commercial names Poliform and Plastozot, polymer composites, reinforced with carbon fibres and leather. The lowest values of the thermal conductivity were measured in the foamed plastic materials, followed by leather; the highest values were measured in the thermoplastic material. The maximum permeability to water vapour was measured in the leather, followed by the polymer foam. The minimum values of the permeability to water vapour were observed for thermoplastic materials and composites. Discussion and conclusions: The results show that the selected orthotic materials had different values of thermal conductivity and permeability to water vapour. An understanding of these properties is essential for selecting the appropriate orthotic materials for a particular application. The wrong choice may adversely affect the patient's skin and comfort while wearing the device. To determine the impact of the use of these materials and consequently their properties on the skin and the patient's well being, it would be necessary to include a study involving patients.