Gas Technology Institute (GTI), with support from the U.S. Department of Energy (DOE) and Brookhaven National Lab, developed and tested a pre-commercial small-scale natural gas liquefaction system. This cryogenic technology has potential use in a variety of applications, ranging from producing fuel for LNG vehicles, remote gas recovery, biogas cleanup and recovery, natural gas peakshaving, and several other specialty natural gas and low-temperature refrigeration markets. This report discusses the design, development, testing, and economics of a pre-commercial liquefaction unit sized to produce 4 m(sub 3)/day (I ,000 gallons/day, gpd).