Compositions for mercury dispensing in lamps are disclosed, comprising a first component comprising mercury and at least a metal selected between titanium and zirconium and a second component consisting of aluminum or either a compound or an alloy including at least 40% by weight of aluminum, wherein the weight ratio between the first and the second component is equal to or lower than 9:1; optionally, the compositions may also include a third component, selected among metals or oxides capable of reacting exothermically with aluminum.