  A method for calculation of the critical temperature of transition of a
many-particle Fermi system into a superfluid or a superconducting state at an
arbitrary pair potential of the interparticle interaction is proposed. An
original homogeneous integral equation, that determines the critical
temperature, is transformed into a homogeneous integral equation with a
symmetric kernel that enables application of a general theory of integral
equations for calculation. Examples are given of calculation of the
superconducting transition critical temperature for the BCS potential with the
Coulomb repulsion and the critical temperature of the superfluid transition of
liquid helium-3 into $p$-wave pairing state for the Morse potential.
