[2] At the 1960 Summer Olympics in Rome he won a silver medal in the 800 m.[3] On 3 August 1955, in the Bislett Stadium in Oslo, Moens improved Rudolf Harbig's 16-year-old 800-meter world record of 1:46.6, running 1.45.7.

In training at night on a tennis court, he ran into a pole, injured himself, and, as world record holder and Olympic favorite, was forced to withdraw from the Games.

Biding his time in the race, Moens followed the pack, waiting to unleash his final sprint in the straightaway.

Coming off the final turn and into the straight, Moens moved strongly into the lead and appeared to have the race won but Snell, a complete unknown at the time, passed him on the left shortly before the finish tape.

"[4] After retiring from competitions Moens served as a sports commentator for VRT; he interviewed his former rival Snell at the 1964 Olympics in Tokyo.