The paper presents a method of evaluation of a time constant that describes relaxational heat exchange between vapour bubbles and superheated liquid. The Scriven equation of bubble growth solved in a numerical way is used to determine the temperature field in the surroundings of the growing bubble. However, initial and boundary conditions are different from those studied before. The heat transfer relaxation time is determined from variations of the average temperature of the superheated liquid surrounding the bubble. Calculations are performed in both Euler’s and Lagrange’s descriptions. The relaxation time obtained in the present paper is compared with the relaxation time reevaluated from the Moby Dick experiment by means of the homogeneous relaxation model.