The association and thermodynamic association parameters for CdBr2 were determined by the conductometric method in pure water and in a mixture of water–ethanol (0.30 mass fraction of ethanol) at different temperatures. The values of ion pair association was also calculated and found that CdBr2 in ceftazidime drug has greater values compared to that in the absence of ceftazidime. Also, the complex formation constants and thermodynamic parameters for complex formation between CdBr2 with ceftazidime as a ligand were also determined by the conductometric method. From the interaction of CdBr2 with ceftazidime, two stoichiometric complexes were obtained 1:1 and 1:2. The complex K f and ΔG f are greater in the case of 1:1 than that of 1:2 (CdBr2/ceftazidime) complexes in 0% ethanol and in 30% ethanol solvents indicating easier complex formation. The formation constants decreased with increased temperature. The negative values of ΔG f for complexation indicate the spontaneity of the complex formation process and that the spontaneity increased with temperature. The negative values of ΔH f show the exothermic nature of the complexation and indicate that the complexation processes are more favored at low temperatures. The ΔS f values for the complexation are positive, confirming that the complex formation is entropically favorable. Significance of the study is to give a lot of data which can be easily obtained for following the very toxic heavy metal cadmium ions.