The case was one of 22 infringement suits Nokia has brought against HTC in Germany, a major battleground in the global patent war between makers of mobile phones, tablet computer devices and their operating software.
"Nokia is pleased with this decision, which confirms the quality of Nokia's patent portfolio," Nokia said in an e-mailed statement. The power-saving patent refers to a technology for saving battery power while connected to a network.
HTC said its business in Germany would not be affected by the Mannheim regional court's ruling as it covers only three handsets the company no longer imports into the country.
It said it would appeal the decision while also continuing efforts to have the patent declared invalid by the German Federal Patents Court and the English Patents Court.
Nokia said it has also asserted the power-saving patent against HTC in the UK and at the United States International Trade Commission, with a hearing in the United States to start in two months.
(Reporting by Harro ten Wolde in Frankfurt and Ritsuko Ando in Helsinki; Writing by Maria Sheahan; Editing by John Stonestreet)