EN
In the paper usefulness of semi-Markovian processes for modelling real processes whichoccur in the operational phase of various technical objects, is considered. The usefulnessof this theory was proved by presenting specific features of the semi-Markovian processesand physical aspects of their use as models of the processes occurring in the operationalphase of the objects in question. The specific features were described with taking intoaccount the process of changing the technical states of such objects. The physical aspectsof models in the form of semi-Markovian processes were justified by postulating a hypo-thesis by which wear process of tribological units of crucial sub-assemblies of machines, can be explained.Also, the consequences logically resulting from the hypothesis and necessary to its verification, are discus-sed. A method for its verification is also attached. It was proved possible to model the real processes inquestion by means of the continuous semi-Markovian processes of finite set of states.