This paper presents the results of model investigation of the heat transfer in plain and combined plain and diagonally finned convective tube banks. A heat and mass transfer analogy, by means of a naphthalene sublimation technique, is used. The effect of tube bank arrangement on heat transfer coefficients and flow resistance is discussed. The results show an increase of Nusselt numbers in comparison to those obtained for plain tube arrangements; however, a significantly higher flow resistance accompanies this increase.