Interest in studying the viscosity of iron and uranium is primarily associated with studying the stability of motion of envelopes made of these materials towards the center in spherically symmetric systems during the acceleration of the envelopes by the products of explosion and by shock waves. The experimental measurements of viscosity in the pressure range from 30 to 250 GPa involve the use of the method of evolution of harmonic oscillation preassigned at the front of shock wave propagating in iron and uranium. The resultant data are considered along with the estimates of the thermodynamic state of matter under shock compression.