In a statement posted on its website, the OPCW said an advance team that accompanied inspectors to Damascus last Tuesday was returning to the Hague after meetings with Syrian authorities.
"Discussions were held with the Syrian authorities on the disclosure which Syria earlier provided to the OPCW on its chemical weapons programme," the statement said.
"The discussions were constructive and the Syrian authorities were cooperative."
Syria handed over the remaining details of its chemical weapons programme to the Hague-based OPCW on September 19.
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Damascus must submit by October 27 its plans for the destruction of all its chemical weapons and facilities, which will then be used to draw up "destruction milestones".
Syria has agreed to relinquish its chemical arsenal for destruction under the terms of a UN resolution that enshrines a US-Russian deal.
The resolution calls for its entire chemical arsenal to be decommissioned by mid-2014.
Damascus agreed to the deal after Washington threatened military action against Syria in response to an August 21 chemical weapons attack.
The Syrian government denies any responsibility, and has suggested that rebels could have carried out the attack.