This study presents a procedure for selecting optimization variables in a Refrigerated Gas Plant (RGP) using Taguchi method with L27 (39) orthogonal arrays. A dynamic RGP model developed under HYSYS environment is utilized as a test bed. This model comprises 762 variables and 21 regulatory control loops. However, only 9 variables or factors with three level each are studied to determine their relative significance in maximizing RGP profit. These factors are prudently selected due to their relevance in maintaining product qualities. Feed Gas (FG) flow rate is found dominant with 97.3 contribution in the first case study. Two additional case studies are performed to magnify the contributions of other factors. FG costs and temperature of FG after coldbox E-101, refrigeration cooler duty and demethanizer reboiler duty are found to be significant factors. © 2010 Asian Network for Scientific Information.