The article presents the methods of formulating and theoretically solving the mathematical problem of designing special clothing that protects against high temperatures in the system “person-special clothing-outdoor environment”. To solve the problem, the human body is assumed to be a deformable cylindrical body of limited size, and special clothing is assumed to be its soft shell. The developed mathematical model makes it possible to predict the dimensions of special clothing, material thickness, cross-sectional area of the underlayer (freedom of clothing) and thermal resistance indicators at the design stage, depending on the air temperature of the external environment.