The SNP leader accepted an invitation to go to the autonomous region in the north-east of Spain as she met the Catalan president Quim Torra during talks at Bute House earlier this year.
SNP MPs have backed Catalonia’s right to hold an independence referendum and Ms Sturgeon has led the widespread criticism of the Madrid government’s hardline approach to blocking the regional government from staging a vote on leaving the Spanish state last year.
The proposed visit to Barcelona, the Catalan capital, emerged in the minutes of a meeting between the First Minister and Mr Torra at the First Minister’s Bute House residence last month, with a date expected to be set in the coming weeks.
But the proposed trip came under fire from Tory MSP Jackson Carlaw.
“As First Minister, Nicola Sturgeon has become utterly side-tracked playing to the Nationalist gallery,” he said.
“It now appears she intends to do that abroad as well as at home. If this is simply a political visit between two separatist parties, there can be no justification for Scottish taxpayers meeting the tab. It should come out of the SNP’s own coffers.”
Ties between the Nationalist movements in Scotland and Catalonia have strengthened over the past year after the case of Clara Ponsati, the St Andrews University professor who was part of the Catalan administration that called the independence referendum last year.
This was thwarted by a hardline crackdown by Madrid last year and Prof Ponsati faced extradition to Spain on charges of rebellion and abusing public funds.
Spanish judges later threw out the case against her and the extradition case was dropped.
Ms Sturgeon’s meeting with Mr Torra was to discuss the case before the resolution.
The minutes of the Bute House event, released under Freedom of Information laws, said the two leaders discussed the “challenging and complex situation” in Catalonia.
“They agreed that the way forward for Catalonia must be through peaceful and democratic solutions involving dialogue between the Spanish and Catalan authorities, respecting the right to self-determination of the Catalan people.
“The president extended an invite to the First Minister to visit Barcelona. The First Minister indicated she would be delighted to do so.”
The Barcelona visit was confirmed by a spokeswoman for the Catalan government, who said there were hopes to fix a date after the summer recess in Catalonia. She said: “It’s true that the last meeting between President Torra and the First Minister was a warm meeting and they agreed on a lot of issues and there was a good relationship between them. The aim [of the visit] is to strengthen that.”
A Scottish Government spokesperson said: “The First Minister had a productive meeting with President Torra and we will look towards opportunities to work together in the future.”