This paper is concerned with model research on the formation of synthetic bonds of humic acids with minerals: Na-montmoryllonite; mica; kaolinite at various pH values (3-7) and in the presence of aluminium ions. The aim of this research was to develop an optimum reaction of suspension for the synthesis of organic-mineral bonds, to study the role of aluminium ions, and to attempt to determine the degree of their complexity on the basis of the specific surface area and of the electrolytic conductivity. An important influence of the suspension pH value on the value of electrolytic conductivity and surface area was observed. The greatest correlation was found in the organic-mineral preparations with kaolinite (r = 0.93***). Generally it can be stated that the degree of reaction of humic acids \with minerals depended most of all on the type of mineral, on the pH value, and on the presence of aluminium.