In this work supercritical fluid extraction (SFE) was used to extract free amino acids (AAs) from sugar beet (SGB) and sugar cane (SGC) molasses. The effect of different variables such as, pressure (150-350 bar), temperature (40-60 degrees C) and extraction time (10-90 min) was evaluated to optimize the extraction using response surface methodology (RSM).The results of SGB and SGC molasses extraction showed that the optimal condition were 184 and 316 bar; 43 and 50 degrees C and 76 and 76 min, respectively. Under the optimum condition, the extraction recoveries of AAs for SGB and SGC molasses were 42% and 31% for aspartic acid, 63% and 37%, for glutamic acid, 46% and 48% for alanine and 31% and 20% for lysine sequentially. This study indicated that SFE might be employed to extract of AAs from SGB and SGC molasses with acceptable selectivity and extraction efficiency.