A flashlight with momentary function and multiple lighting modes wherein a mechanical switch is activated by a pushbutton so that each depression of the pushbutton causes the switch to cycle through a first state, a second state and a third state sequentially. When the switch is in the first state or the second state, it is electrically connected to the respective port of the integrated circuit and the integrated circuit drives the light source to operate in the respective lighting mode; when the switch is in the third state, it is electrically disconnected from the integrated circuit and the integrated circuit drives the light source to operate in a third lighting mode. When the integrated circuit detects that the switch is disconnected from the integrated circuit after a state which corresponds to the OFF mode and is therefore transitioning to a subsequent state, it drives the light source to operate in the lighting mode of the subsequent state.