The composting of household sewage sludge is one of the methods of their rational management. However, in order that the process is successful, it is necessary to supplement sludge with structural materials as well as with other biowastes. During the composting process, organic matter is degraded and nearly all parameters of the composted mixtures, including macroelements, undergo changes. That is why the aim of the performed experiments was to determine the direction of changes in the organic carbon content as well as in total quantities of nitrogen, phosphorus, potassium, sodium and calcium occurring in the course of composting. The composting process was carried out using sewage sludge supplemented with hem wastes or/and straw and wood chips and lasted 224 days and during this time the samples for chemical analysis were collected. It was demonstrated, among others, that the strongest influence on the content of the analyzed constituents was exerted by the time (days) of composting and, to a lesser extent, by the type of composts. No statistical significance was demonstrated concerning the interactions of experimental factors on concentrations of the analyzed chemical elements.