ISE Corporation ("International Space Enterprises",[1] later "Innovative Solutions for Energy")[2] was a manufacturer and integrator of heavy-duty hybrid electric powertrain systems for transit bus and truck use, based in San Diego and later Poway, California.

ISE was founded in 1995 and filed for bankruptcy in 2010, shortly after raising $20 million in its initial public offering on the Toronto Stock Exchange.

[3] ISE Corporation was founded in January 1995[4] by David M. Mazaika and Michael C. Simon,[5] engineers who had formerly worked for General Dynamics.

The second, ISE Research, was dedicated to developing hybrid electric powertrains for heavy-duty transportation applications (Class 6 and up trucks, tow tractors, transit buses).

The HHICE bus used a Ford Triton V10 gasoline engine that had been converted to burn hydrogen, coupled with an electric generator as the APU for the series hybrid system; it was first tested by SunLine Transit Agency.