One of the methods of the platinum recovery from industrial wastes is the solid-liquid extraction by cyanide solution at high temperatures and pressures. So far, few studies have been conducted in the field of scientific survey of this process, so that some aspects of this process such as the kinetics of the reaction of platinum with sodium cyanide are completely unknown. Accordingly, this research was conducted to study the platinum recovery process from spent catalysts in a fixed bed reactor using solid-liquid extraction by cyanide solution. At the first step, kinetics of thermal decomposition of the cyanide ions in a sodium cyanide solution at high temperatures was studied. The kinetics experiments were carried out under various operating conditions, including the temperature of the solution (120, 140, and 160°C ), and the initial concentration of the cyanide solution (1 and 3.5 wt%). The obtained kinetic data were fitted into an empirical power–law rate equation and kinetic model parameters were evaluated using the experimental data via a non-linear regression analysis. The values of reaction rate order with respect to the cyanide ion and activation energy are 1.63 and 115.9 kJ/mol, respectively. The average error of kinetic model in predicting the experimental data is %9.7. At the second step, the kinetics of platinum extraction from spent catalyst in cyanide solution at temperatures between 100 and 180 ?C was experimentally studied. Based on the design of experiments via response surface methodology (RSM) by computer simulating software “Minitab 16 ” , experiments were carried out at operating conditions including five solution temperatures, five initial concentrations of cyanide solution and five liquid/solid weight ratios. The obtained kinetics data were fitted into an empirical power–law rate equation and the kinetics model parameters were evaluated by using experimental data via non-linear regression analysis. The reaction orders with respect to platinum and cyanide ions were calculated to be 3.62 and 0.192, respectively. Also the activation energy for this reaction was calculated to be 39.54 kJ/mol. The average error of kinetic model in predicting the experimental data is %16.73. At the final step and for surveying the dynamic behavior of a fixed bed reactor with continuous operation, experiments were carried out in a fixed bed reactor in different conditions at varying leaching temperature, cyanide solution concentration and volume flow rate of solution. Next a dynamic mathematical model was developed for platinum extraction in a fixed-bed reactor and the model was programmed and coded for simulation of the process through a homemade modeling environment in Matlab 7.11.0 (R2010b) software. The predicted results by the model are in good agreement with the experimental data with a relative absolute error of less than 10%. This model was applied in assessing the effect of operating parameters. The results show that the optimum values of the inlet sodium cyanide solution temperature and concentration are 160 °C and 1 wt%, respectively. Also varying the volume ?ow rate of solution and Distribution of cyanide solution along the length of the reactor through side stream have no effect on platinum recovery efficiency.