[9] It is the most prominent dialect to employ voseo (the use of vos in place of the pronoun tú, along with special accompanying conjugations) in both speech and writing.

As Rioplatense is considered a dialect of Spanish and not a distinct language, there are no credible figures for a total number of speakers.

Rioplatense is mainly based in the cities of Buenos Aires, Rosario, Santa Fe, La Plata, Mar del Plata and Bahía Blanca in Argentina, the most populated cities in the dialectal area, along with their respective suburbs and the areas in between, and in all of Uruguay in the form of Uruguayan Spanish.

In the northeast of Uruguay there exists a variety of Portuguese influenced by Rioplatense Spanish, known as Riverense Portuñol.

Several languages, especially Italian, influenced the historical criollo Spanish of the region because of the diversity of the settlers and immigrants to Argentina and Uruguay: European settlement decimated Native American populations before 1810 as well as during the expansion into Patagonia (after 1870).

Aspiration of /s/, together with loss of final /r/, tend to produce a noticeable simplification of the syllable structure, giving Rioplatense informal speech a distinct fluid consonant-vowel-consonant-vowel rhythm: [citation needed] Rioplatense Spanish, especially the speech of all of Uruguay and the Buenos Aires area in Argentina, has intonation patterns that resemble those of Italian dialects.

[20] This correlates well with immigration patterns, since both Argentina and Uruguay have received large numbers of Italian settlers since the 19th century.

According to a study conducted by National Scientific and Technical Research Council of Argentina[21] Buenos Aires and Rosario residents speak with an intonation most closely resembling Neapolitan.

The researchers note this as a relatively recent phenomenon, starting in the beginning of the 20th century with the main wave of Southern Italian immigration.

One of the features of the Argentine and Uruguayan speaking style is the voseo: the usage of the pronoun vos for the second person singular, instead of tú.

The second person plural pronoun, which is vosotros in Spain, is replaced with ustedes in Rioplatense, as in most other Latin American dialects.

Although literary works use the full spectrum of verb inflections, in Rioplatense (as well as many other Spanish dialects), the future tense tends to use a verbal phrase (periphrasis) in the informal language.