We demonstrate our airwriting interface for mobile handsfree text entry. The interface enables a user to input text into a computer by writing in the air like on an imaginary blackboard. Hand motion is measured by an accelerometer and a gyroscope attached to the back of the hand and data is sent wirelessly to the processing computer. The system can continuously recognize arbitrary sentences based on a predefined vocabulary in real-time. The recognizer uses Hidden Markov Models (HMM) together with a statistical language model. We achieve a user-independent word error rate of 11% for a 8K vocabulary based on an experiment with nine users. Author Keywords Gesture recognition, handwriting recognition, human computer interaction, wearable computing, accelerometers ACM Classification Keywords H.5.2. Information Interfaces and Presentation: User Interfaces; I.5.4 Pattern Recognition: Applications General Terms Performance, Algorithms, Experimentation