An instrument and associated method are disclosed for the accelerated synthesis of peptides by the solid phase method. The instrument includes a microwave cavity, a microwave source in communication with the cavity, a column in the cavity formed of a material that is transparent to microwave radiation, a solid phase peptide support resin in the column, respective filters for maintaining the solid phase support resin in the column, a first passageway for adding starting compositions to the column, a second passageway for removing compositions from the column, and a third passageway for circulating compositions from the column into the third passageway and back to the column.