Triethylborane is prepared by the reaction of trimethyl borate with triethylaluminium:[1] The molecule is monomeric, unlike H3B and Et3Al, which tend to dimerize.

[1] Triethylborane was used to ignite the JP-7 fuel in the Pratt & Whitney J58 turbojet/ramjet engines powering the Lockheed SR-71 Blackbird[2] and its predecessor, the A-12 OXCART.

[4] The Merlin engines that power the SpaceX Falcon 9 rocket use a triethylaluminium-triethylborane mixture (TEA-TEB) as a first- and second-stage ignitor.

It reacts with metal enolates, yielding enoxytriethylborates that can be alkylated at the α-carbon atom of the ketone more selectively than in its absence.

[10] Triethylborane reacts with methanol to form diethyl(methoxy)borane, which is used as the chelating agent in the Narasaka–Prasad reduction for the stereoselective generation of syn-1,3-diols from β-hydroxyketones.

[11][12] Triethylborane is strongly pyrophoric, with an autoignition temperature of −20 °C (−4 °F),[13] burning with an apple-green flame characteristic for boron compounds.