Carbon paste electrode (MCPE) modified with novel Carboxymethyl chitosan/poly(1-cyanoethanoyl-4-acryloyl thiosemcarbazide) copolymers (CMCS-PCEATS) was prepared for determination of iron(II). The interaction between the modifier (CMCS-PCEATS) and iron(II) ions at the electrode surface was characterized using scanning electron microscope (SEM), the energy dispersive X-ray analyzer (EDX) and FTIR. Effect of different plasticizers (TCP, o-NPOE, FPNPE, DBP, DOP and DOS) and content of modifier were studied. The best performance was obtained with the electrodes plasticized with FPNPE (electrode I) and TCP (electrode II)Under the optimized conditions, the electrodes reveal Nernstian slopes of 30.21 +/- 0.31 and 30.17 +/- 42 mV decade(-1) over a wide concentration range from 1.0 x 10(-7) to 1.0 x 10(-1) mol L-1 with a detection limit of 1.0 x 10(-7) mol L-1 at pH range from 3 to 8 for electrodes I and II. The paste is enough stable for 37 days without any measurable divergence in the potential. This method was successfully applied for potentiometric determination of iron (II) in pharmaceutical and water samples, and the results obtained agreed with those obtained with spectrophotometer and inductive coupled plasma (ICP). The thermal stability as well as the antimicrobial activity of the MCPE and MCPE-iron(II) were also studied. The results illustrated that MCPE-iron(II) was thermally stable over wide range of temperature than MCPE and it has higher antibacterial activity against Streptococcus aureus, Salmonella SP., Escherichia coli and antifungal activity against Candida albicans.