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Abstract A method for calculating the performance of low-temperature separation plants is discussed, and comparisons of calculated recoveries with those observed during field testing of an installation are shown. The ability to calculate plant performance is of considerable value as a variety of possible operating programs can be investigated at little cost. The close agreement between calculated and observed plant recoveries suggests that with reasonable diligence plant performance can be calculated within generally accepted engineering accuracy. However, as over-enthusiastic employment of calculations can lead to serious error, calculated results should be supplemented with sufficient field or laboratory test data to provide adequate experimental verification. Introduction Within the past few years the use of low-temperature separation and stabilization units to increase the recovery of condensate from gas streams has increased greatly. Although the principle of cold separation is simple, the processing that is required to separate the hydrocarbon stream into the gas and liquid fractions resulting in the greatest over-all economy of operation is sometimes complicated, and the equipment used for this purpose is often expensive. Frequently, several hydrocarbon streams of varying (and in many cases, unknown) composition are mixed prior to processing through a plant. As a result, the most desirable operating conditions have not always been selected, and unexpected operating difficulties have developed. It seems plausible that a better understanding of lowtemperature processing and removal of much of the aforementioned uncertainty can be achieved by replacing rule-of-thumb analyses with convenient and usable calculation techniques. Therefore, the discussion which follows is designed to demonstrate that liquid hydrocarbon recovery resulting from processing light hydrocarbon mixtures through the type of low-temperature and stabilizer equipment commonly encountered in the Gulf Coast area may be calculated with sufficient accuracy for many engineering purposes.