The enthalpy of reaction of the 2-chloroethylideneaminocarbamic acid ethylester formation from chloroacetaldehyde and hydrazinoformic acid ethylester in ethanol at the temperature of 298.15 K has been determined by a microcalorimeter. Experimental results gave the enthalpy of formation Delta H-r(m)theta = (-16.07 +/- 0.079) kJ mol(-1), the reaction order of this reaction n = 1; the rate constant k = 1.190 x 10(-3) s(-1) and the free energy of activation DeltaG(not equal)(theta) = 89.718 kJ mol(-1). The result indicates that the reaction takes place easily at room temperature.