Abstract At work is followed the dissolution steel process in pig iron. Process have two phases: solidification, joint with incresing of the immersed steel weght and dissolution, joint with weight decreasing. The work follows this process in dependence on time, pig iron temperature and weight of the dissolution steel. The kurves shows the kinetics of dissolution and of steel, which define the changes of the examinational corpuscle weight at the time. The kurves they have its characteristic fashion. Occur on they several point, which characterise parameters this process. The work describes the changes of curves and the changes of this quantity in dependence on time, temperature and weight of the examinational corpuscle. This work describes the relation between indenpendently variables and dependently variables of this process.