Introduction: In addition to their original function, prosthetic accesssories function as a barrier between the environment and patient's skin. Two properties of the material from which the accessory is made are crucial for patient’s comfort: thermal conductivity and water vapour permeability. Human body maintains a constant body temperature through sweating, so it is very important that materials enable water permeability and ensure a dry environment around the residual limb to help prevent dermatological problems. Purpose: The purpose of this graduation thesis is to determine thermal conductivity and water vapour permeability of the selected prosthetic materials. Based on measurement results and data found in the relevant literature, we estimated the effect of the examined properties (thermal conductivity and water vapour permeability) of prosthetic materials on patient's comfort. Methods: Water vapour permeability was determined by an experiment, conducted in compliance with the requirements of SIST EN ISO 7783:2018. Measurements of thermal conductivity (or thermal transmissivity) complied with the requirements of SIST EN 12667:2002. Thermal conductivity was measured using a device made of two plates with different temperatures, between which a sample of the material was inserted. For measuring water vapour permeability, measuring cups were used. We weighed the cups in a certain time interval, thus determining water transmission through the tested material from the area with higher humidity to the area with lower humidity. Results: The experiment included selected materials, which prosthesis is made of, i.e. polyethylene, polypropylene, Plastazote, Polyform, and carbon fibre reinforced polymer composite. We also measured the materials used for prosthetic socks. Thermal conductivity values were the lowest for foamed thermoplastic materials, ranging from 0.03 to0.09 W/mK. The highest values were measured for non-foamed thermoplastic materials, ranging from 0.12 to 0.22 W/mK. Foamed materials are more water permeable (μ = 46 for Plastozote) than non-foamed polymer and carbon fibre reinforced composites (μ > 2000). Discussion and conclusion: The selection of an appropriate accessory is especially important for patients’s comfort and well-being, as it allows them to avoid dermatological problems, which may arise as a result of the humid and hot environment inside the prosthesis. The results showed that materials have different properties that vary considerably, and that more recently developed materials are made with the intent to increase thermal conductivity and water vapour permeability. Since actually perceived comfort depends on the patient, we believe that further research would benefit from their cooperation.