"I will be very much insisting and pushing for... A serious discussion on political transition" at the upcoming round, de Mistura told reporters.
The United Nations had previously said the negotiations aimed at ending the five-year conflict would resume on April 11.
At the last round, which ended on March 24, the Damascus regime insisted it was premature to have a concrete dialogue on creating a transitional government, while the main opposition High Negotiations Committee (HNC) put forward its plan towards forming a new government.
"I need to verify the international and regional stakeholders' position" in order to have "concrete results in the next round of talks", de Mistura said, adding that he expected to be back in Geneva on April 12 or 13.
The main obstacle in the negotiations is the future of President Bashar al-Assad.
The HNC has said Assad must go before a transitional government is agreed, while the regime insists his fate be excluded from the talks.
He also plans to meet Turkish officials in Europe by the middle of next week.
Ankara has emerged as one of Assad's main foes.
The UN envoy said he has not requested a face-to-face meeting with Assad in Damascus, but expects to hold talks with Foreign Minister Walid Muallem.
De Mistura added that two of his staffers are currently in Riyadh to meet with the HNC.
The negotiations set for next week will be the third round this year, including a round that was aborted in February as violence raged on the ground.
More than 270,000 people have been killed in Syria and millions have fled their homes since the conflict erupted in March 2011.
