A transparent cylindrical bed was employed for the investigation of the attrition of zeolite molecular sieves in a slugging fluid bed. A carefully planned factorial design was performed for the investigation of the attrition occurring in fluidized beds. The reduction of attrition of the molecular sieves by the addition of fine solid lubricants was also investigated. The hydrodynamic behavior in each run of the factorial design was monitored by measuring certain dependent variables, such as the slug height and the slug frequency. The results of the factorial design contributed to the development of a phenomenological model able to predict the attrition and the reduction of attrition in fluidized beds.