Effects of different K/Ca ratios on the growth, yield and physiological characteristics in Galia (Cucumis melo var. reticulatus L. Naud. cv. Galia) grown in hydroponics were evaluated. The experiment was arranged in a completely randomized design of three replicates. Melon seeds were sown in a medium containing perlite and vermiculite (3:1 V:V) and then irrigated with water containing different K/Ca ratios of: 1.5, 2, 2.5, 3, 3.5, 4. The yield and such plant's physiological characteristics as chlorophyll index and petiole nitrate were assessed. Plants were finally cut and such vegetative characteristics as leaf area, fresh and dry weight measured. The results revealed that the melon yield was significantly affected by various K/Ca ratios, so that the highest yield was observed in ratio 3 (6.25 kg/ per plant), while the lowest was for ratio 4. Leaf area (LA) was significantly affected by various K/Ca ratios, with maximum LA achieved for ratio 3. A positive correlation was observed between leaf area and yield (R2=0.62). The fresh and dry weight of leaf and stem as well as petiole nitrate content were significantly affected by various K/Ca ratios. The percentage of Total Soluble Solids (TSS) was significantly affected by various K/Ca ratios, with the maximum TSS being achieved for the ratio 4 treatment. It was finally concluded that K/Ca ratio 3 treatment was the most effective in improving the growth, yield and physiological characteristics of Galia, so that the adjustment of K/Ca ratio in the nutrient solution at this level seems to be fundamental in obtaining the highest and optimum yield.