Behavior of the turbulized mixtures at the stage of their inertial motion (with removed acceleration) has been studied. Turbulized mixtures were obtained at the contact boundary of two different density fluids as a result of the Rayleigh–Taylor instability (RTI) development. At some instant of time t*, the acceleration sign was changed and conditions for the mixture separation were created. Then at the instant of time t**, the acceleration was removed and the turbulized mixture continued to move under force of inertia. Experiments have been performed at the installations EKAP and SOM. At the stage of inertial motion, the average density distribution of substance in the mixture region and the width of the turbulized mixture region have been obtained. The data on the mixture region expansion at the stage of inertial motion have been obtained as well.