W/O emulsions were formulated with a vegetable oil and a water phase containing a polysaccharide and glycerol in order to reduce the loss of a phytosanitory product during its spraying on plants and therefore the amount used. Different kinds of polysaccharides were tested (CMC, guar and xanthan) and two kinds of surfactants were used (lecithin and PGPR). The stability of the emulsions was determined by different techniques bottle test, optical microscopy, laser granulometry and differential scanning calorimetry - whose principle is based on the correlation between the freezing temperature of the droplets and their radius. From the experiments performed by varying different parameters, a formulation of a suitable emulsion was developped 3% of CMC in the water phase, 50-70% V/V of water, 10-12% of PGPR. The release within a few minutes of the required amount of CMC in water checked by conductivity was obtained by adding another surfactant commercially named Cynthiorex.