Entitled “Phai Ve Dam” (Phai Draws Dam), the works on display were collected by Thai collector Tira Vanictheeranont.
The collection not only includes paintings portraying Nguyen Ba Dam - the artist's friend - but also some other friends' portraits and newspaper illustrations.
"It is a rare chance for people to see popularly the works by Phai," collector Truong Nhuan said.
"A few exhibitions were made several decades ago by collectors Tran Hau Tuan in 1988 and Nguyen Manh Phuc in 2007 in Hanoi on the occasion of the 10th and the 20th anniversary of the artist's death."
Dam is now 96 years old and still living in Hanoi. He was one of Phai's closest friends and was sketched more than 240 times.
The old teacher's face and personality was what Phai was looking for in a muse to explore inner Hanoians, with his solemn yet witty demeanour and crooked nose on a square face.
Phai drew his friend wherever and with whatever material he had to hand, such as ink pen, colour pencil, ink, ballpoint pen and oil pencil, among others.
The works include a sketch by Phai to test a new pencil given to him by Dam, one of many small sketches on display.
Phai made his name by creating art on Hanoi's Old Quarter. He was born in Hoai Duc district on the outskirts of the capital on September 1, 1920.
He was among the last artists to graduate from the Indochina Fine Arts College in 1941-1945.
Nguyen Ba Dam and Thai collector Tira Vanictheeranont
As well as his famed oil-on-canvas paintings, he also had success with other themes including cheo (traditional opera) and portraits. He used many materials such as canvas, paper, wood and even old newspapers due to a lack of material.
Phai won various awards at National Fine Arts Exhibitions and Hanoi Fine Arts Exhibitions many times. His illustrations on cheo won the book design prize at the Leipzig Book Fair in 1982.
He died on 1988 in Hanoi. In 1996, he was posthumously awarded the Ho Chi Minh Prize in literature and arts.
An award was launched in 2008 named "Bui Xuan Phai Award - For The Love of Hanoi" to honour his career and to spread his love for Hanoi. The awards are well respected and honour the contributions of individuals and organisations to society, culture and the arts in Hanoi.
The late artist was commemorated with a doodle on google.com on Sunday on the occasion of his 99th birthday anniversary.
The Thai collector Tira Vanictheeranont came to Vietnam 27 years ago as a private supplier of hardware to the HCM City Power Company. He became a collector in 2006 in retirement.
The Bui Xuan Phai exhibition runs till September 6 at Chon Auction House, 63 Ham Long Street, Hanoi.