The numerous manufacturing processes for HCOOH can be divided into those in which formic acid is the main product of the process and those where it is obtained as a byproduct. At present, formic acid is primarily manufactured by direct synthesis.

When manufacturing formic acid directly, one starts with CO, which is either hydrolyzed to HCOOH or reacted with alcohols to form formic acid esters:

In hydrolysis or alcoholysis, the above equilibrium is displaced towards the formate side by bases such as NaOH or Ca(OH)₂. Consequently, the process can be operated at 8-30 bar CO pressure and 115-150 °C. Synthesis gas can be employed instead of pure CO. The free HCOOH is obtained from its salts by acidification followed by distillation or extraction with, for example, . This process has been used since 1989 in a 40000 tonne-per-year plant in the CIS.

The reaction of CO with alcohols, preferably methanol, is the first step in the most well-known production route for formic acid. This, in contrast to the carbonylation of methanol to acetic acid, can be formally regarded as the insertion of CO in the O-H bond of methanol, and takes place with catalytic amounts of sodium methylate at about 70°C and 20-200 bar. With an excess of methanol, CO conversions of up to 95% with nearly 100% selectivity to methyl formate can be obtained.

The best known methyl formate processes practiced commercially have been developed by BASF, Halcon-SD, and Leonard. These are very similar in the carbonylation step, but differ from each other in the formic acid autocatalyzed hydrolysis at 80-140 °C and 3-18 bar. The largest differences are to be found in the operational procedures used to minimize the re-esterification of the product formic acid with the recycle methanol.

In order to prevent this re-esterification, a detour is generally made by synthesizing by reaction of methyl formate with NH3 at 80-100°C and 4-6 bar. Formamide is then hydrolyzed.

The hydrolysis of formamide takes place continuously above 80°C with 70% H₂SO₄ to form HCOOH and (NH₄)₂SO₄:

The separation of the reaction product takes place in a drum-type furnace. The purification of the stripped acid is carried out using a stainless steel or polypropene column with a silver or graphite condenser.

A process of this type was developed by BASF and operated commercially until 1982, when it was replaced by direct hydrolysis.