The understanding of electrokinetic transport phenomena in microfluidic dispensers, an important component of biochips, is very important for designing and controlling biochips. A theoretical model to study the electrokinetic transport processes in microfluidic dispensers was developed in the work to study the controlling parameters for the dispensing process. The electrical field, the flow field, and the concentration field during dispensing processes were obtained by solving this theoretical model numerically. The effects of the electroosmotic mobility of the buffer solution, the diffusion coefficient and the electrophoretic mobility of the sample, the applied electrical field strength, and the channel size on the dispensing process are examined in this paper. The investigations show that optimal controlling parameter values can be found by using this model for dispensing any desired amount of the sample.