This volume contains the papers presented at the 26th OpenMath Workshop held in July 2014 in Coimbra, Portugal. These papers were accepted for presentation and discussion: the conclusions and any developments to OpenMath can be found in the minutes of the meeting at http://www.openmath.org. There were 7 submissions. Each submission was reviewed by at least 2 referees, all program committee members. The committee decided to accept 6 papers.