Development Thillana Mohanambal was a novel written by
Kothamangalam Subbu under the pseudonym "Kalaimani". It was
serialised in the Tamil magazine
Ananda Vikatan in 1957–58. The story portrayed the relationship between Mohanambal, a celebrated dancer, and Shanmugasundaram, a
nadaswaram musician. The illustrations for the novel were done by sketch artist and cartoonist,
Gopulu.
S. S. Vasan, who held the rights to the book, twice refused to allow director
A. P. Nagarajan to make a film adaptation of it because Vasan wanted to produce a film adaptation himself under his banner
Gemini Studios. When Nagarajan approached him for the third time, Vasan gave him the rights without any consideration. Nagarajan paid Vasan (about US$3,300 in 1968), but also went to visit Subbu with an additional (about US$1,300 in 1968). Subbu declined the money, saying that Vasan had forwarded him the money Nagarajan had paid earlier. Nagarajan's version of the film had a few creative differences from the novel; one of the significant ones was where the film ended with Mohana and Shanmugasundaram's marriage while the novel, in contrast, had a tragic ending. Nagarajan produced the film under his production company, Sri Vijayalakshmi Pictures.
K. S. Prasad was in charge of the film's cinematography, M. N. Rajan and T. R. Natarajan jointly handled the editing, and Ganga was the film's art director. R. Rangasamy was lead actor
Sivaji Ganesan's make-up artist.
Casting Padmini was cast as Mohanambal, the title character. A younger artist was suggested instead of Padmini for the role, but Nagarajan refused to replace her. Ganesan attended
Carnatic music concerts, and consulted Carnatic musicians in preparation for his role.
T. S. Balaiah portrayed Muthurakku, the
Thavil player. Tiruvidaimarudur Venkatesan played the instrument
thavil off-screen for Balaiah. Balaiah had additional training for playing the instrument.
A. V. M. Rajan portrayed Thangarathnam, the second
nadaswaram player in Sundaram's troupe. Nagesh, in an article published in
Kalki in 2004, revealed that Subbu initially created the character of Vaidhi with himself in mind.
Manorama, who played the folk dancer Karuppayi alias Jil Jil Ramamani, stated that she was initially nervous acting in front of Ganesan and Balaiah, but Nagarajan assured her that whenever her character appeared she would be the centre of attention, which gave her the confidence to play her role. Serial and theatre artist M. L. Bhanumathi played the nurse who treats Shanmugasundaram. Other supporting actors included
K. Sarangapani,
Filming Thillana Mohanambal, shot in
Eastmancolor, was filmed in
Thanjavur,
Thiruvarur and
Madurai, in the
Cauvery delta. Many of the film's aesthetics were borrowed from Indian theatre, of which Nagarajan was an artist. The competition sequence between Ganesan and Padmini took about nine takes to be filmed. The film presented a
mise-en-scène feel, mostly using frontal shots. The actors were lined up to face the camera and deliver their dialogue. Nagarajan, a former employee of the T. K. S. drama company, paid tribute to Shankardas Swamigalfrom whom the company had its ancestral rootsby naming a drama company in the film after the company's name. Snippets of the film's behind-the-scenes production were filmed by French film director
Louis Malle as a part of his 378-minute, seven-part documentary series, ''
L'Inde fantôme: Reflexions sur un voyage'' (1969), when he visited Madras (now
Chennai). As Sundaram, Ganesan did not actually play the
Nadaswaram; he moved his fingers on the surface of the instrument, held his breath intermittently, and created an illusion on the screen with his facial expressions. The
Nadaswaram played by Sundaram and Thangarathnam was played off-screen by the brothers, M. P. N. Sethuraman and M. P. N. Ponnusamy. Nagarajan had seen the duo performing at a wedding reception in
Karaikudi and asked them to come to Chennai. Nagarajan then listened to a radio recital by the duo, and was impressed with their rendition of
Tyagaraja's
Keerthana, "Nagumomu Ganaleni". The Keerthana was later selected as one of the soundtrack instrumentals in the film. Real locations were mixed with the fictional town of Madhanpur. The film also had undertones of the
Chithirai festival. Its final length was . == Music ==