Local media said as many as 8,000 police officers were being deployed today for the visit by Zhang Dejiang, the Communist Party's No 3 official.
He's the most senior Chinese official to come to Hong Kong in five years.
About 100 protesters chanted slogans demanding Beijing stop interfering in Hong Kong's affairs and burned a sign calling for Zhang to be kicked out of Hong Kong as they marched toward the convention center where Zhang was giving a keynote speech.