The complexes of Cu(II), Co(II), Zn(II), and Cd(II) with 9-ethyl-3-carbazolecarboxaldehyde-4-phenyl-3-thiosemicarbazone were synthesized and their stability constants were determined using a spectrophotometric method at different temperatures (25, 30, 35 and 40+/-0.1 degrees C) and ionic strengths (0.05, 0.01 and 0.20 M KNO3) in 50 % (v/v) aqueous DMF. From these constants, the thermodynamic stability constants and thermodynamic parameters (Delta G degrees, Delta H degrees and Delta S degrees) were calculated.