The main aim of the present investigation was to determine retention behavior and interactions of oligonucleotides with alkylamide stationary phase. Five oligonucleotides, differing in the sequence, were tested. Changes in the composition of the mobile phase, i.e. pH (5.0−7.0) and buffer concentration (30−75 mM) were investigated in detail. In addition, the hydrophobic and electrostatic parameters were measured for the different pH’s and salt concentrations. The theoretical model of interactions between individual elements of the separation system, (e.g. solute, stationary phase, and mobile phase) based on zeta potential measurements, hydrophobic and electrostatic parameters calculation, and molecular modeling, has been considered.