Techno-thrillers (or technothrillers) are a hybrid genre, drawing subject matter generally from spy/action thrillers, fantasy/war novels, and science fiction. They include a disproportionate amount (relative to other genres) of technical details on its subject matter (typically military technology); only science fiction tends towards a comparable level of supporting detail on the technical side. The inner workings of technology and the mechanics of various disciplines (espionage, martial arts, politics) are thoroughly explored, and the plot often turns on the particulars of that exploration.

Techno-thrillers tend to have a broad scope in the narrative, and can often be regarded as contemporary speculative fiction; world wars are a common topic. Techno-thrillers often overlap, as far as the genre goes, with near-future science fiction. To the extent that technology is now a dominant aspect of modern global culture, most modern thrillers are "techno-thrillers", and the genre is somewhat diffuse. The category of techno-thriller blurs smoothly into the category of hard science fiction; the defining characteristics of techno-thriller are an emphasis on real-world or plausible near-future technology and a focus on military or military-political action.