The topic of the diploma thesis is the treatment of selected materials from recycled technical textiles with a flame retardant. The work includes the issue of technical textiles in terms of their characteristics, including their composition with respect to an overview of the properties of individual components. It also deals with the basic ways of distribution of flame retardants as well as an approximation of the main principles of their effect. The diploma thesis contains a brief division of thermal insulation materials and their basic characteristic with a focus on thermal insulation materials from recycled textile textiles. It also includes the characteristics of selected test methods focused on acoustic, thermal insulation, fire and technical parameters of materials. The experimental part of the diploma thesis brings the resulting data from the performed methods of testing recycled technical textiles treated with a flame retardant and their subsequent comparison in order to determine their overall benefits and effectiveness. This part also fulfills the goal of the work.