A toner for developing an electrostatic image is formed from toner particles containing at least a binder resin, a colorant and an organometallic compound. The binder resin in the toner particles has a tetrahydrofuran-insoluble (THF-insoluble) content of at most 5.0 wt.% based on the binder resin. The toner has a glass transition temperature of 50.degree.-80.degree. C. The toner further has storage modulus characteristics including a storage modulus at 80.degree. C. (G'.sub.80) of 1.times.10.sup.4 -5.times.10.sup.6 �dyn/cm.sup.2 !, a storage modulus at 130.degree. C. (G'.sub.130) providing a ratio G'.sub.80 /G'.sub.130 of 10-5.times.10.sup.3, and a storage modulus curve showing a minimum (G'min) in a temperature region of 110.degree.-190.degree. C. The toner especially exhibits excellent low-temperature fixability, anti-high temperature offset characteristic, storage stability and color-miscibility.