Lebedev made his doctoral degree in Strasbourg under the supervision of August Kundt in 1887–1891.

Along with Indian physicist Jagadish Chandra Bose he was one of the first to investigate millimeter waves, generating 50 GHz (6 mm) microwaves beginning in 1895 with a spark oscillator made of two platinum cylinders 1.5 cm long and 0.5 diameter immersed in kerosene at the focus of a parabolic reflector, and detecting the waves with an iron-constantan thermocouple detector.

[3] With this apparatus, he extended the work of Heinrich Hertz to higher frequencies, duplicating classical optics experiments using quasioptical components such as lenses, prisms and quarter-wave plates made of sulfur and wire diffraction gratings to demonstrate refraction, diffraction, double refraction, birefringence and polarization of millimeter waves.

The discovery was announced at the World Physics Congress in Paris in 1900,[4] and became the first quantitative confirmation of Maxwell's theory of electromagnetism.

[5] In 1909, he reported that the pressure of light on gas is in agreement with predictions based on Maxwell's theory.