Combine sugar and water in a medium saucepan; cook, stirring constantly, over medium heat 5 minutes or until sugar dissolves. Remove from heat, and cool completely.
Meanwhile, remove rind from orange with a vegetable peeler, being careful not to get the bitter white pith. Cut rind into strips, and set aside.
Process cranberries in a food processor 2 minutes or until very finely chopped. Combine sugar solution, orange rind, and cranberries in a 1-gallon jar; stir in vodka. Cover with lid, and store in a cool, dark place for 1 month.
Line a wire-mesh strainer with 2 layers of cheesecloth; strain liqueur through cheesecloth into a bowl. Discard solids. Carefully pour liqueur into clean bottles or jars.
Note: Cranberry Liqueur can be stored in a cool, dark place for up to a year.