The paper discusses the results of experimental studies on the coalescence of toluene as well as silicone oil drops of different viscosity and the results of model predictions. The coalescence model, based on assumption of partially mobile drop interfaces, has been applied for toluene as well as for silicone oil of mu(D) = 10 mPa s, and three different models for immobilized drop interfaces were proposed for silicone oil of high viscosity, AD = 500 mPa s. Multifractal formalism was used to take into account local intermittency. Drop size distributions were predicted by solving the population balance equation. Assumption of partial mobility gives very good results for toluene and quite good for silicone oil of low viscosity. It was also shown that for silicone oil of high viscosity drop size distribution cannot be precisely predicted by one simple model because drops of different size behave in a completely different way. However, the proposed models allow one interpret experimental observations.