The British No 2 and world 17 stormed past Jan Apell of Sweden 6-3, 6- 2. It was only Henman's second victory on his least favourite surface this season. Britain's world No 5, Greg Rusedski, has failed to win a match on clay this year.
Also through are the former French Open champions, Michael Chang and Sergi Bruguera. Chang, the 11th-seeded American, needed three sets to overcome David Prinosil of Germany 6-4, 3-6, 6-1 in a battle between two wild cards. Bruguera defeated fellow Spaniard Jacobo Diaz 6-2, 6-1.
Chang, who was out of action in March with a knee injury, said of his fitness. "I've been fortunate in my career that I've had few major injuries."
Marcelo Rios has declared himself fit again after an elbow injury led to the loss of his world No 1 ranking and he has now set his sights on winning the French Open title next month.
The 22-year-old from Chile, who is the top seed in Hamburg this week, is keen for a return to action after he was unable to defend his title in Monte Carlo last month. His absence there led to him handing back his top ranking to Pete Sampras - the American won the ATP event in Atlanta on clay on Sunday.
"It's a little bit sore but I'm feeling much better and I'll try to play this week,'' Rios said of his injury. "I feel pretty good and have a lot of energy to play, but I'll take it carefully. It was a bad injury."