Melchnau is a municipality in the Oberaargau administrative district in the canton of Bern in Switzerland.

Between the 12th and 15th centuries, Grünenberg Castle was a cultural and political center for the nobility that ruled over much of the Oberaargau region.

After the war, the lands and castles were returned to the Grünenbergs after they entered into a treaty with Bern.

However, the family's power continued to weaken and in 1444 they sold the lands that belonged to Grünenberg castle to Bern.

In 1452 the last male Grünenberg heir, Wilhelm, died and in 1480 the family sold Langenstein castle to Bern.

[5] After the Grünenberg lands were absorbed by Bern, it became part of the Bailiwick of Aarwangen.

[3] Until the Protestant Reformation, the village was part of the parish of Grossdietwil in the Canton of Lucerne.

In the 18th and 19th centuries, traditional agriculture was partially replaced by linen weaving, straw plaiting and shoe manufacturing (until 1960) in the local economy.

[3] In the last century, Melchnau has developed from a farming town to a municipality with a diversified economy.

In 1917 a narrow-gauge railway was opened between Langenthal and Melchnau, which was superseded by buses in 1982.

[8] The blazon of the municipal coat of arms is Argent a Mount of Six Coupeaux floatant Vert.

[12] Most of the population (as of 2000[update]) speaks German (1,514 or 90.7%) as their first language, Serbo-Croatian is the second most common (59 or 3.5%) and Turkish is the third (30 or 1.8%).

The historical population is given in the following chart:[3][15] The Käserstock and the Stock des Birlihofs are listed as Swiss heritage site of national significance.

The number of jobs in the primary sector was 65, of which 63 were in agriculture and 2 were in forestry or lumber production.

In the tertiary sector; 70 or 28.0% were in wholesale or retail sales or the repair of motor vehicles, 11 or 4.4% were in the movement and storage of goods, 12 or 4.8% were in a hotel or restaurant, 3 or 1.2% were the insurance or financial industry, 8 or 3.2% were technical professionals or scientists, 20 or 8.0% were in education and 111 or 44.4% were in health care.

[12] From the 2000 census[update], 219 or 13.1% were Roman Catholic, while 1,144 or 68.5% belonged to the Swiss Reformed Church.

This is followed by three years of obligatory lower Secondary school where the students are separated according to ability and aptitude.

Following the lower Secondary students may attend additional schooling or they may enter an apprenticeship.