The secretary-general of Merkel's Christian Democratic Union, Hermann Groehe, said talks with the left-leaning Social Democratic Party were held in a "good, sober and constructive atmosphere" and a second meeting would take place Oct 14.
Groehe said the meeting focused on the common ground between the parties, not their differences. During the campaign, the Social Democrats' main candidate, Peer Steinbrueck, had called for a national minimum wage and tax increases for high earners both of which Merkel's conservatives have rejected.
A coalition with the SPD, which won 25.7 per cent of the vote, would have a healthy parliamentary majority and ensure Merkel a third term. But many grassroots Social Democrats and some in the party leadership are wary of again being the junior partner in a "grand coalition" like the one that governed Germany during Merkel's first term from 2005 to 2009.
Last week, SPD leaders said they would consult the party's 470,000 members before agreeing to any deal.
But an agreement with the Greens is believed less likely because the two sides have never had a coalition at the national level and are considered ideologically far apart on many issues.
"We want to reach a timely decision because it's clear that coalition talks will also take some time," Groehe said. "We want to be thorough, but at the same time we know this country needs clarity.