We demonstrate our airwriting interface for mobile hands- free text entry. The interface enables a user to input text into a computer by writing in the air like on an imaginary black- board. 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.