Kobozevs main focus was on catalysis and thermodynamics. The main problem in catalysis development has been the lack of a single generalized theory. Kobozev believed that the catalysis theories of his time were incapable of producing a common mechanism because they failed to explain the nature and structure of the active centers. He saw the main issue of the contemporary catalysis theories in the concept of crystalline nature of catalytic activity. In 1934 he introduced the term electrocatalysis'.
In 1939, connecting the kinetic analysis method with the heterogenous catalysis, he introduced the theory of active ensembles which regarded how many atoms of metal catalyst can produce a catalytically active center.
In his research he had estimated the minimal number of catalytically active atoms in aggregates for some chemical reactions. He argued that the active centers were factored by energy rather than crystalline structures.
He called the minimal group of atoms showing catalytic activity active ensemble. However, he believed that the motion of such active ensembles was limited by special migration areas. Kobozev showcased how the number of atoms in an active ensemble and the average rate of a migration area could be determined by a change in specific activity  I  on the spread of a catalyst over the surface of a carrier. His study had revealed a connection between the typical heterogenous catalysis and the activity of complex enzymatic catalysts. In 1936 together with A. M. Dubrovskaya, Kobozev demonstrated that regular promoters on the surface of a catalyst are in larger concentration, than inside the phase, while in some cases promoter's presence on the surface brings about decline in catalytic activity.
It had been discovered that in heterogenous catalysis a solid body engages in the reaction not by the entire surface but by a small part of some active surface elements acting in the background of the large inactive crystalline mass of a catalyst. Kobozev had noticed that for some catalysts active surface was only 0.05%, therefore, he had supposed that such active centers were not crystalline but small groups of random atoms. Consequently, he had concluded that catalytic activity takes place not in the crystalline, but the amorphous, precrystalline, phase.
He had also noticed that the crystalline phase was made of a cellular, or mosaic, structure – an aggregate made of closed cells (migration areas) surrounded by energetic and geometrical barriers impermeable to atoms of the surface, thus remaining isolated. Getting into migration area, as if hollows, atoms gather at the bottom, i.e. in place of maximum adsorbsion potential, creating ensembles. So formed ensembles of atoms of a certain composition, are active centers on an inactive catalytic carrier Kobozev had studied dissolution of active substance on an inert carrier and found out that increased dissolution resulted in rise in catalytic activity, while minimum of active substance brought about formation of maximally active catalysts. Kobozev had also proposed a formula calculating the number of atoms engaged in active centers.
Kobozevs research showed that the most active ensembles consisted of 2 or 3 atoms, which corresponded with Balandins theory.
Kobozev and his students argued that activation of catalyst particles for the reaction has two factors: adsorbsion, i.e. interaction of an ion or atom with particles of a catalyst, and formation of an active center, i.e. interaction of catalyst's particles, which can, however, play separately.
Catalysts activity can be significantly increased by including larger and thermadynamically unstable masses, which he named aggravation (1946) when increase of catalysts activity is factored by complication of its molecule (increase of molecular mass). So he and his co-workers tried to explain superactivity of enzymes in catalysis.
Kobozev's theory of active ensembles contradicted the contemporary works on the relationship between activity and dispersion in catalysis  which argued that catalytic activity of a solid body was higher with rise in the level of dispersion.
Further research of the relationship between dispersion and catalytic activity showed that crystalline structures, indeed, had catalystic activity, and his theory hadnt been accepted. Kobozevs catalysts had been proved to be of little production potential, while crystalline catalysts used in industry were fully accepted for their high output.
Kobozev's theory is believed to be practically implemented only if the amount of metal catalyst is small and the object has a block shape.
Kobozev expressed the idea of recuperation of energy that, held by the group of atoms connected to the active center, can partly activate molecules of a new substrate contacting the catalyst.
Kobozev took part in developments by professor Shpitalsky regarding the theory of intermediate products in the homogenous catalysis. Based on catalytic and enzymatic degradation of hydrogen peroxide, Kobozev showcased how studying the results of kinetic research can reveal the chemical composition and physical properties of those intermediate products that had before been only vaguely assumed in literature.