Hyperphosphatemia, hyperkalemia, and fluid overload are frequently observed and pose major physiological concerns in chronic kidney patients. The problems are closely related to inadequate diet and phosphate binder intake, which are considerable challenges for many patients. The objective of this study was to develop and test an educational decision support system to help kidney patients cope with diet restrictions and phosphate binder dosage. A prototype was designed including three main functions: 1) information and education, 2) food analyser database and diet registration, and 3) model-based decision support to phosphate binder dosage. The functions and the usability of the prototype were evaluated through user testing and qualitative interviews including five kidney patients. The decision support function was modified and tested using experimental data. In conclusion, the system was evaluated to be a relevant, and potentially beneficial tool to cope with kidney diet restrictions. Further data are necessary to validate the correct phosphate binder dosage and assess the ability of the system to decrease the incidence of fluid and electrolyte disorders in kidney patients.