The solubility of 1-keto-1,2,3,4-tetrahydro-6-methylcarbazole (KTMC) in acetone in the temperature range from 18 to 55 C was determined by the residue solid technique and the polythermal method using a heat flow calorimeter with turbidity measurement capacities. The results were correlated using a polynomial equation. Utilizing the polythermal method, the metastable zone has also been determined. The broadening of the metastable zone with increasing cooling was observed from 0.05 to 2.0 degrees C center dot min(-1).