The first exhibition opened earlier this month at Oriel Tegfryn in Menai Bridge. The Anglesey gallery first opened in 1963, one of the oldest commercial galleries in the country, and was bought by Tinney in 2010.
The summer show continues until August 28 with works available from £50 to £40,000.
Martin Tinney Gallery opened in Cardiff in 1992. Its summer show runs from August 2-September 2 and celebrates Welsh artists of the past and present such as Gwen John, Augustus John, John Piper and Ceri Richards.
The exhibitions are part of a larger annual programme of monthly events at each location, including solo shows and a rotating stock of painting on display and in store.