Sorption of copper ions on a synthetic zeolite NaX was examined depending on different initial concentrations of copper (II) nitrate and copper (II) chloride solutions. The experiment was conducted in batch reactors at a constant temperature of 306 K, stirring speed of 200 rpm, for 3 hours. It was observed that for the sorption of copper ions from a solution of copper (II) nitrate, the sorption capacity increases rapidly with an increase in the initial concentration of copper ions until the concentration of 22.909 mmol dm-3 and slightly changes at the higher concentrations. In the case of copper ions sorption from a solution of copper (II) chloride, the sorption capacity increases all the time with an increase in the initial concentration of copper ions and reaches its maximum sorption capacity at the highest selected concentration. The analysis of the obtained results for both solutions shows a constant decrease in the sorption efficiency of copper ions on the zeolite with an increase in the initial concentration. It was also observed that the sorption efficiency of copper ions from copper (II) chloride solution is consistently higher than the sorption efficiency of copper ions from copper (II) nitrate solution for all initial concentrations except for the lowest selected initial concentration. To make the assessment as precise as possible the maximum experimental capacity of sorption of copper ions and value of the statistical parameters calculated, RMSE and χ2 were also taken into account. Taking everything into account all of the above, it can be concluded that the best agreement with the experimental data is shown by the Toth isotherm for the sorption of copper ions from a solution of copper (II) nitrate, while the best agreement with the sorption of copper ions from a solution of copper (II) chloride is achieved by using the Langmuir isotherm.