The detailed thermodynamic cycle of-the NH3-NaSCN absorption refrigeration unit is presented, based on the thermodynamic properties of the working media. Correlations are developed, which express the coefficient of performance and the cooling capacity in terms of the required evaporation temperature, T-ev, and the available ambient temperature, T-amb. A nomograph is also presented, which shows in a compact form the behaviour of the NH3-NaSCN system and allows direct estimation of its main characteristics. It is concluded that if (T-amb - T-ev) varies from 0 to 40 degrees C, the theoretical coefficient of performance decreases linearly from 95 to 77%. For the same range of (T-amb - T-ev) the theoretical cooling capacity varies from 1150 to 1300 kJ/kg NH3 if T-ev varies from 0 to -15 degrees C. Under the conditions examined, for T-amb - T-ev > 23 degrees C, the coefficient of performance of the NH3-NaSCN system becomes higher than that of the NH3-LiNO3 system. The observed increase reached 4% at T-amb - T-ev = 40 degrees C.