A spectral General Circulation Model at horizontal resolutions T21 and T42 has been integrated upto 30 d on 16 and 32 processors of Meiko T800. The model at resolution T21 is also implemented on 16 processors (T800) of a parallel computer (CHIPPS). The wall-clock timings of model integration for 1, 10 and 30 d are noted and the speedup and efficiency of 16 and 32 processors have been computed.