The species has mainly grey upperparts and white underparts, darker on the tips of the flight feathers and with a yellow cere.
Young birds are darker.
Adults have a body length of 30–45 cm and a wingspan of 85–95 cm, and weight 350–600 g. Females are larger.
The call of the grey falcon consists of hoarse chattering, clucking and whining sounds, similar to the peregrine falcon but slower and deeper.
Calls include a loud, slow ‘kek-kek-kek’ or ‘kak-ak-ak-ak’.

Both of the collectors of Gould's specimens were effusive in their praise of this falcon's appearance, Sturt's field note says it had a 'delicate beauty', and when Gilbert obtained his second specimen in August 1842 he wrote,
I assure you I never gazed with more delight on any Specimen I ever Shot, than on this Bird, as it lay in the grass, throwing up its feet to prevent my hand reaching it.

— John Gilbert, Letter to Gould.
October, 1842.
The species has mainly grey upperparts and white underparts, darker on the tips of the flight feathers and with a yellow cere. Young birds are darker. Adults have a body length of 30–45 cm and a wingspan of 85–95 cm, and weight 350–600 g. Females are larger. The call of the grey falcon consists of hoarse chattering, clucking and whining sounds, similar to the peregrine falcon but slower and deeper. Calls include a loud, slow ‘kek-kek-kek’ or ‘kak-ak-ak-ak’.
Both of the collectors of Gould's specimens were effusive in their praise of this falcon's appearance, Sturt's field note says it had a 'delicate beauty', and when Gilbert obtained his second specimen in August 1842 he wrote,
I assure you I never gazed with more delight on any Specimen I ever Shot, than on this Bird, as it lay in the grass, throwing up its feet to prevent my hand reaching it.
— John Gilbert, Letter to Gould. October, 1842.
Grey falcon