Abstract: A method of GC-MS for determination of phenols in water was proposed. The sample was extracted by passing through microcolumn packed with modified polymer of styrene-divinylbenzene, then derivatized with pentafluorobenzyl bromide. The derivates were separated on DB-5MS capillary column, and determined by MS with negative chemical ionization and under selected ion monitoring mode. Values of limit of detection (3S/N) were found in the range of 0.03-0.09 μg·L-1. Using water sample as matrixes, tests for recovery were made at 3 concentration levels, values of recovery found were in the ranges of 64.9%-87.8% with RSD′s (n=7) in the range of 4.9%-17%.