Vitamin B12 is a very important micronutrient essential for health (due to its functions) supplied by the diet, mostly, from animal sources. Its deficiency may cause critical health problems, whereby it is important to incorporate this vitamin in food supplements and additives. On the other hand, vitamin B12 is a sensitive compound and can be easily degrade during food process and storage. Through microencapsulation it is possible to overtake some of these limitations and improve its application in food industry. The aim of this work was to produce microparticles with vitamin B12 (1, 2,3,4 and 5% (w/w)) and to study its release namely in simulated gastric conditions (SGF). Modified chitosan was chosen as encapsulating agent, considering its biocompatibility and good solubility in water. The microparticles were prepared by a spray-drying technique and then characterized in terms of morphology (Scanning Electron Microscopy - SEM) and particle size (Laser Granulometry Analysis). An UV spectrophotometric method was validated, to evaluate the vitamin release and its stability. The average diameter of the particles varies with vitamin concentration, ranging from 3 to 8 mu m, considering the differential volume distribution, and from 0.1 to 0.9 mu m considering the differential number distribution. The product yield of the spray-drying process was around 57% for the microparticles with vitamin. The SEM images show microparticles with a regular round shape and a smooth surface. The release time increases with increasing of pH, and decreases with decreasing temperature. The Weibull kinetic model fits very well the experimental results obtained in SGF at 37 degrees C. Microparticles stability was evaluated after 3 and 6 months and a small decrease in the amount of vitamin released was observed. Vitamin losses are <10% for 3 months and <20% for six months storage. So, microparticles of vitamin B12 with a good stability can be produced by spray -drying using modified chitosan. (C) 2017 Elsevier B.V. All rights reserved.