A freezing device for cryopreservation of blood mononuclear cells has been developed. The device is microcontroller operated, allowing cell freezing by a fully automatic, unattended process. To ensure optimum preservation, the temperature in the cell suspension uniformly decreases from room temperature to
$-100^{\circ}$
C and then the samples are transferred to long‐term storage. The performance of the device has been tested using both physiological solution and a sample of cell suspension. The control of temperature variation of cell suspension in the entire temperature range has been realised with an accuracy better than
$\pm$
0.1%. The viability of cells recovered from the frozen samples was 95%. The nitrogen consumption for one cycle of cryopreservation was 1.5l. In addition to the fully automatic mode, the manual and semi‐automatic modes are available for research purposes. The device has been designed using low cost and widely used electronic components and materials, it is compact and simple to operate.
