Apart from the ratification, they also talked about EU enlargement and Croatia's relations with its neighbours.
Lidington voiced hope that Great Britain would complete the ratification of the Accession Treaty by the end of May 2013. He said special attention would be paid to the policy chapters "Judiciary and Fundamental Rights" and "Justice, Freedom and Security".
Pupovac said Croatia certainly would not become an EU point of entry for foreigners, but said this was both a Croatian and a European issue and that Croatia expected the EU's help in the matter.
Mondekar and Pupovac said EU enlargement to the east was of strategic importance for Croatia, notably in light of the fact that the Croatian-Bosnian border would be the longest border dividing an EU member from a non-member country.
Lidington agreed that EU enlargement must continue, saying Great Britain had been supporting that process since Margaret Thatcher's times, but under strict criteria and rules.
The EU's door is open to everyone willing to adjust and adopt European standards, he said.
Discussing the recent elections in Serbia, both sides spoke with caution about Tomislav Nikolic's election as president.
That, of course, doesn't mean that we won't continue to cooperate and talk, said Mondekar and Pupovac.
Lidington said special attention would be paid to Nikolic's stance on Kosovo and Bosnia and Herzegovina.