Robert Downey Jr.'s son was arrested in West Hollywood on Sunday (29.06.14).

The 'Iron Man' and 'Avengers' star's eldest child Indio, 20, was detained by police officers after they noticed he was smoking a suspicious substance from a pipe while riding in the passenger seat of a car.

A deputy of the Los Angeles County Sherriff's department pulled the vehicle over and allegedly found cocaine in Indio's possession and he was promptly arrested.

Indio - whose mother is Robert's ex-wife Deborah Falconer - was released after midnight at a cost of $10,000 bail.

Robert has previously battled drug addiction and has spoken often about the effect narcotics had on his personal life and career.

The star was introduced to marijuana at the age of six when his father allowed him to use the drug and he was later arrested on numerous occasions on charges related to marijuana, cocaine and heroin.

In the 1990s, Robert infamously explained to a judge regarding his drug addiction: ''It's like I've got a shotgun in my mouth with my finger on the trigger, and I like the taste of the gun metal.''