Physicists on Wednesday said they had found a new sub-atomic particle consistent with the Higgs boson, which is believed to confer mass.
The particle is "consistent with (the) long-sought Higgs boson," CERN said in a statement, adding that further data was needed to identify the find.
Scientists have wrestled with the elusive particle for nearly half a century.
"We have reached a milestone in our understanding of nature," said CERN Director General Rolf Heuer.
"The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle's properties, and is likely to shed light on other mysteries of our Universe."
Finding the Higgs would validate the Standard Model, a theory which identifies the building blocks for matter and the particles that convey fundamental forces.
It is a hugely successful theory but has several gaps, the biggest of which is why some particles have mass and others do not.
Mooted by British physicist Peter Higgs in 1964, the boson is believed to exist in a treacly, invisible, ubiquitous field created by the Big Bang some 13.7 billion years ago.
When some particles encounter the Higgs, they slow down and acquire mass, according to theory. Others, such as particles of light, encounter no obstacle.