We study the possibility of detecting halo cold dark matter through the annihilation process &khgr;&khgr;→&ggr;&ggr;. This process produces monoenergetic &ggr;‐rays, and many be a clear signature of particle dark matter. If there is a closure density of photino ‐so far a favoured candidate ‐we show that it will be very difficult to observe this annihilation line from a satellite or space station borne experiment. On the contrary, triplet neutrinos which have recently been suggested as a plausible solution of the dark matter conundrum, whilst elusive at accelerators, should produce a clear &ggr;‐ray line signal, well above background.