Gretzenbach is a municipality in the district of Olten in the canton of Solothurn in Switzerland.

Gretzenbach is first mentioned in 778 as Grezzinbach though this comes from a 10th Century copy of the older original.

[4] Gretzenbach has an area, as of 2009[update], of 5.8 square kilometers (2.2 sq mi).

Of the rest of the land, 1.22 km2 (0.47 sq mi) or 21.0% is settled (buildings or roads), 0.05 km2 (12 acres) or 0.9% is either rivers or lakes.

[5] The municipality is located in the Olten district, on a terrace through which the Aare river has eroded a number of channels.

It consists of the village of Gretzenbach, the settlement of Weid and, since 1973, the former municipality of Grod.

The blazon of the municipal coat of arms is Argent a Fir Tree Vert trunked proper issuant from a Mount of 3 Coupeaux of the second.

[9] Most of the population (as of 2000[update]) speaks German (2,203 or 92.1%), with Italian being second most common (72 or 3.0%) and Albanian being third (25 or 1.0%).

[8] The age distribution, as of 2000[update], in Gretzenbach is; 228 children or 9.5% of the population are between 0 and 6 years old and 465 teenagers or 19.4% are between 7 and 19.

[9] The historical population is given in the following chart:[3][14] In the 2007 federal election the most popular party was the SVP which received 40.42% of the vote.

In the federal election, a total of 931 votes were cast, and the voter turnout was 57.0%.

[9] There were 1,271 residents of the municipality who were employed in some capacity, of which females made up 42.5% of the workforce.

In the tertiary sector; 85 or 44.3% were in wholesale or retail sales or the repair of motor vehicles, 12 or 6.3% were in the movement and storage of goods, 19 or 9.9% were in a hotel or restaurant, 2 or 1.0% were in the information industry, 1 was the insurance or financial industry, 9 or 4.7% were technical professionals or scientists, 21 or 10.9% were in education and 5 or 2.6% were in health care.

[9] From the 2000 census[update], 1,008 or 42.1% were Roman Catholic, while 799 or 33.4% belonged to the Swiss Reformed Church.

The education system in the Canton of Solothurn allows young children to attend two years of non-obligatory Kindergarten.

All the lower secondary students from Gretzenbach attend their school in a neighboring municipality.