Following LIGO results of intermediate mass black holes mergers, the idea that dark matter is composed of Primordial Black Boles (PBH), made a recent comeback.
PBHs might be formed in the early Universe through a variety of mechanisms, best known being the gravitational
collapse of overdense regions due to density fluctuations. It's widely accepted that black hole loose there mass over time through the Hawking radiation process.
Since the particle emission rate increases with black hole temperature, PBH
evaporation is a runaway process that eventually leads to a violent explosion. It has been argued that a class of ultra short gammay ray bursts are actually PBH explosions. The current upper limits on the local PBH explosion rate lie in the $10^4$--$10^5$ $\mathrm{pc}^{-3}$ $\mathrm{yr}^{-1}$ range.

This contribution reports on the search for TeV $\gamma$-ray bursts with a timescale of a few seconds, as expected from the final stage of PBHs evaporation, using 2700 hours of H.E.S.S. extragalactic observations. We present the search algorithm, statistical estimations strategies and results of this analysis.