In mixed refrigerant Joule–Thomson (MR J–T) cryocooler, the recuperative heat exchanger is used to cool the refrigerant prior to its expansion which governs its performance. However, at present, the design of the heat exchanger is crucial due to lack of experimental heat transfer data and generalized empirical correlations for boiling and condensation of the mixed refrigerants. In the present work, experiments are conducted on MR J–T cryocooler using multi tubes-in-tube and tube-in-tube helically coiled heat exchanger for the same mixtures. The objective of the work is to study the effects of heat exchanger on the overall performance of MR J–T cryocooler. The refrigeration temperatures and cool down time for steady temperatures of the cryocooler using both the heat exchangers are compared. It is found that the overall performance of a J–T cryocooler depends on thermal and hydraulic behavior of the heat exchanger.