The Kuznetsov NK-88 was an experimental alternative fuel turbofan engine, designed by the Kuznetsov Design Bureau.
Development of the NK-88 began in 1974 at the Kuznetsov Design Bureau. It was a modification of the NK-8-2U two-spool low-bypass turbofan and was designed to run on liquid hydrogen (LH2). A further development of this engine, the NK-89, was designed to run on both liquified natural gas (LNG) and kerosine.
On April 15, 1988, one NK-88 running on cryogenically stored LH2[1] was tested in flight in the starboard nacelle of the Tupolev Tu-155 flying laboratory. The other two nacelles contained engines of the native NK-8-2 type and ran on kerosene.