  We consider killed planar random walks on isoradial graphs. Contrary to the
lattice case, isoradial graphs are not translation invariant, do not admit any
group structure and are spatially non-homogeneous. Despite these crucial
differences, we compute the asymptotics of the Martin kernel, deduce the Martin
boundary and show that it is minimal. Similar results on the grid $\mathbb Z^d$
are derived in a celebrated work of Ney and Spitzer.
