The cap is convex to flat, dark red to blackish brown, very much paler when dry and grows up to 5 cm (2.0 in) in diameter. The gills are white, later reddish and quite crowded. The spores are variable in colour, white, pink, brown have all been observed. The stipe is a similar colour to the cap, thin, and velvety at the base. The flesh is white and has a smell of freshly cut cucumbers.
Macrocystidia cucumis was originally described in Europe where it is most common, and it is also known from North America, Australia and New Zealand. It can be found in forests, disturbed grounds and gardens and its preferred substrate is wood debris.