A demultiplexer (DMUX) is a key subsystem of rapid single flux quantum (RSFQ) circuits and systems in practical applications. High-speed data from RSFQ circuits should be converted into sufficiently low-speed ones for transmission to and processing by room temperature electronics. We designed, fabricated and successfully tested an RSFQ DMUX based on the synchronous shift-and-dump architecture whose advantages are modularity and compactness. A 1-to-8 DMUX was implemented using our standard cell library on 1.6 kA cm(-2) Nb trilayer technology. Fully functional operation was confirmed by low speed testing. Experimental bias margins were as large as +/-16%. Results of average voltage measurements implied that the DMUX was operated at data rates up to 25 Gb s(-1).