An unemployed man, described by police as confused, sprayed Rembrandt's famous painting "The Night Watch" with an unidentified chemical today, but museum officials said damage was minimal.
It was the second attack on the priceless artwork in nearly 15 years, and the third this century.
Dutch Television said the spray was concentrated sulfuric acid, but museum officials would not confirm the report.
Immediately after the attack, a museum guard applied a neutralizing agent, and the damage to the 1642 masterpiece appeared limited to surface veneer, Rijksmuseum spokesman Piet van Thiel said.
Museum guards seized the attacker and handed him over to police. The painting is guarded around the clock by an unarmed security company worker.
Police said they do not know what prompted the attack.
Spokesman Klaas Wilting said the 31-year-old suspect is a Dutch national from The Hague. The man, not identified by name in line with police policy, is being held on suspicion of vandalism.
"He is confused and not telling us anything at the moment," Wilting said shortly after the attack.
Barry Olshen of Toronto, Canada, said he was standing among a group of museum visitors and right next to the man, who was wearing a long, hooded tan coat. The vandal pushed his way through the crowd to a steel barrier about two yards in front of the painting.
Suddenly he took a "little spray pump he had been concealing in his hand" and sprayed the painting, Olshen said.
The chemical dripped over an area of almost a square yard, covering it in white splotches.
Van Thiel said the painting will be taken to a secret location for restoration but will probably be on display in about two weeks.
The painting has been under permanent guard since 1979, when it was put back on display after a four-year restoration period that followed a knife attack Sept. 14, 1975. A Dutch schoolmaster claiming to be on a divine mission made several deep slashes in "The Night Watch." He was never tried but committed to a mental asylum, where he later committed suicide.
During World War I, an unemployed shoemaker made several knife slashes in the artwork to protest his inability to find work.
"The Night Watch" measures 12 feet by 14.5 feet and shows a gathering of 17th-Century militiamen. It is believed to commemorate celebrations surrounding the 1638 visit to the Dutch capital by French Queen Maria de Medici.
The museum has never placed a value on "The Night Watch," which is not insured, in line with Culture Ministry policy.