A simple mathematical model is presented for a box-type solar cooker with outer-inner reflectors. It is based on analytical solution of the energy-balance equations for different elements of the cooker. The cooker performance is investigated by computer simulation in terms of the cooker efficiency as well as characteristic and specific boiling times. Numerical calculations have been carried out for different tilt angles of the outer reflector on a typical winter day (20 January) in Tanta, latitude 30 degrees 47＇ N. The optimum tilt angle of the outer reflector is 60 degrees. At the optimum tilt angle of the outer reflector, the specific and characteristic boiling times are decreased by 50 and 35%, respectively, compared to the case without the outer reflector. The overall utilization efficiency of the cooker is 31%.