With regards to the synthesis of L-Dopa (l-3,4-dihydroxy phenylalanine) two types of biosensors were designed by immobilizing tyrosinase on conducting polymers; polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT). PPy and PEDOT were synthesized electrochemically and tyrosinase immobilized by entrapment during electropolymerization. The kinetic parameters of the designed biosensors, maximum reaction rate of the enzyme (Vmax) and Michaelis Menten constant (Km) were determined. Vmax were found as 0.013 for PPy matrix and 0.041 mol/min.electrode for PEDOT matrix. Km values were determined as 3.7 and 5.2mM for PPy and PEDOT matrices respectively. Calibration curves for enzyme activity vs. substrate concentration were drawn for the range of 0.8 to 2.5 mM L-Tyrosine. Optimum temperature and pH, operational and shelf life stabilities of immobilized enzyme were also examined.