| Official Name: | Štvrtok na Ostrove |
| Other Name: | Csallóközcsütörtök |
| Settlement Type: | village |
| Pushpin Map: | Slovakia |
| Pushpin Label Position: | none |
| Pushpin Mapsize: | 250 |
| Pushpin Relief: | 1 |
| Pushpin Map Caption: | Location of the village |
| Coordinates: | 48.1°N 17.35°W |
| Subdivision Type: | Country |
| Subdivision Type1: | Region |
| Subdivision Name1: | Trnava |
| Subdivision Type2: | District |
| Subdivision Name2: | Dunajská Streda |
| Established Title: | First written mention |
| Established Date: | 1217 |
| Named For: | Thursday |
| Government Footnotes: | [1] |
| Leader Party: | Party of the Hungarian Coalition |
| Leader Title: | Mayor |
| Leader Name: | Péter Őry |
| Area Total Km2: | 13.06[2] |
| Elevation M: | 128[3] |
| Population Footnotes: | [4] |
| Population Total: | 1700[5] |
| Population Est: | 1751 |
| Pop Est As Of: | 2008 |
| Population Density Km2: | 130.64[6] |
| Demographics Type1: | Ethnicity |
| Demographics1 Title1: | Hungarians |
| Demographics1 Info1: | 82.85 % |
| Demographics1 Title2: | Slovaks |
| Demographics1 Info2: | 12.33 % |
| Timezone: | EET |
| Utc Offset: | +1 |
| Timezone Dst: | EEST |
| Utc Offset Dst: | +2 |
| Postal Code Type: | Postal Code |
| Postal Code: | 930 40 |
| Area Code: | +421 31 |
| Population Density Sq Mi: | 50.44 |
| Area Total Sq Mi: | 5.04 |
| Elevation Ft: | 420 |
Štvrtok na Ostrove (Hungarian: Csallóközcsütörtök, in Hungarian pronounced as /ˈtʃɒlːoːkøztʃytørtøk/, formerly Hungarian: Csütörtök) is a village and municipality in the Dunajská Streda District in the Trnava Region of south-west Slovakia.
The village is in the Danubian Lowland and is in the western part of Žitný ostrov (Csallóköz). The municipality lies at an altitude of 128 metres and covers an area of 13.066 km2.
In the 11th century, the territory of Štvrtok na Ostrove became part of the Kingdom of Hungary. The earliest extant document about the village dates back to 1217, in which it was referred to it by its Hungarian name as Villa Ceturthuc. In the thirteenth century German settlers arrived in the village who named it Loipersdorfin. The village enjoyed Royal privilege to collect tolls and in the fifteenth century it gained the status of a town and had the right to hold markets and develop crafts and trades. Today Štvrtok na Ostrove is a basically agricultural village.
Until the end of World War I, it was part of Hungary and fell within the Somorja district of Pozsony County. After the Austro-Hungarian army disintegrated in November 1918, Czechoslovak troops occupied the area. After the Treaty of Trianon of 1920, the village became officially part of Czechoslovakia. In November 1938, the First Vienna Award granted the area to Hungary and it was held by Hungary until 1945. After Soviet occupation in 1945, Czechoslovak administration returned and the village became officially part of Czechoslovakia in 1947.
In 1910, the village had a population of 1228, mostly Hungarians.
At the 2001 Census the recorded population of the village was 1679 while an end-2008 estimate by the Statistical Office had the village's population as 1751. As of 2001, 82.85% of its population was Hungarian while 12.33% was Slovak.
As of 2001, 93.81% of the inhabitants professed Roman Catholicism.