  Monochromatic gamma-ray signals constitute a potential smoking gun signature
for annihilating or decaying dark matter particles that could relatively easily
be distinguished from astrophysical or instrumental backgrounds. We provide an
updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to
such signals, based on observations of the Galactic centre region as well as of
selected dwarf spheroidal galaxies. We find that current limits and detection
prospects for dark matter masses above 300 GeV will be significantly improved,
by up to an order of magnitude in the multi-TeV range. This demonstrates that
CTA will set a new standard for gamma-ray astronomy also in this respect, as
the world's largest and most sensitive high-energy gamma-ray observatory, in
particular due to its exquisite energy resolution at TeV energies and the
adopted observational strategy focussing on regions with large dark matter
densities. Throughout our analysis, we use up-to-date instrument response
functions, and we thoroughly model the effect of instrumental systematic
uncertainties in our statistical treatment. We further present results for
other potential signatures with sharp spectral features, e.g.~box-shaped
spectra, that would likewise very clearly point to a particle dark matter
origin.
